S-BLOCK ELEMENTS - GROUP 1 & GROUP 2 In One Shot | WB HS Class 11 Chemistry | Abhiyaan Bangla 2.0 💯

0:00 Hello my dear students welcome to PW Bangla I have come to you ma'am today for revision and practice of another chapter of class eleven semester one so today we will see S block elements so let's start see before that let me tell you something that is we have studied the periodic table in these S block elements we know that in the periodic table we divide it into four blocks we get S PDF all these block elements which we get will be studied separately which we are starting

0:46 with S block which two groups are studying in S block the two groups in S block are group one and group two group one contains alkali metals group two contains alkaline earth metals what do you think hey ma'am when you said what topic will be covered you have not started the topic at all actually come to this block chemistry maximum The problem that students have is how much to read, how many reactions to remember, how to answer questions, so I will tell you a few things. First of all, you have to

1:31 read these places very well. You have to read them. Yes, you have to understand the concept. But then there are some other topics that are related to the trends and the compounds that these elements are forming. Questions also arise from them. For example, in Group One, you have NaOH, then your baking soda, then you have washing soda. For these things, you have to read those reactions. Their preparation. There are some specific points from which

2:17 questions come repeatedly. So you have to read this place. You have to know a lot of information. If you do n't read it, it is not possible to know. And in Group Two, there is also Caulichoon, Hydroxide Plaster of Paris. This is the thing that I want to say. This batch of Ovian 2 that you are seeing right now is part of this campaign. You can find the previous batch on the PW Bangla channel if you go to the playlist where I taught these two groups separately in details, okay, group one and group two. So if you watch them once, then the entire content that is important will be revised once

3:03 and that is why today's class. That is why I have thought of making today's class a little question answer based because it is already explained in details there and you will listen to it and you will be able to read it, but how the questions come and how we can answer those questions very easily. That is why what we will do today is we will revise the question based topics. So today's topic will be covered by MCQs and since MCQs will come in your semester one, so MCQ practice. Yes, I will tell you some important points. There is no need to worry, but through MCQ practice, we will revise the summary of this chapter. Okay, let's start now.

3:51 First, let's see what I said. Let us briefly look at some points. The first points are some common reactions in the case of group one, which raise questions. We will also look at similar common reactions in group two. Before that, let me tell you a page about which elements are in the S block. Look at the S block. In this case, we will see that the general electron configuration of the outer shell is N S 1 2 2. That is, whenever we look at group one, there will be one electron in the valence cell and that electron has entered the S subshell. That is why we

4:39 call them S block elements here. And we will see in group two, in which there will be two electrons in N S. This is the N we are talking about. Here, N is the principal quantum number. Now, let us look at the alkali metals in group one. What do we call all these elements of group one? Alkali metals are lithium, sodium, potassium, rubidium, cesium, and here in group two, we will see the alkaline earth metals. Alkaline earth metals, there we will see beryllium magnesium calcium strontium barium, who has the angular relationship,

5:25 but the question comes, you see here, you will understand that the angular relationship between lithium and magnesium is that their angular relationship is right. Now we will look at some points, then we will look at those important places according to the question. Look, first there is the reaction with oxygen. In the reaction with oxygen, lithium forms a common oxide, that is, monoxide. This lithium monoxide is right. That means that in the reaction with oxygen, what does lithium usually form? It forms monoxide, it forms

6:11 lithium monoxide and it forms sodium peroxide. Look, here it is written sodium peroxide and the rest of those that have M M for this element, that is, the metals are called. In place of that M, potassium, rubidium or cesium can be used. They form superoxide. Now we will see that this is We are talking about three types of oxides, usually lithium monoxide, sodium peroxide and potassium rubidium cesium. They form superoxide. In the case of ordinary oxides or monoxides, oxygen shows a minus two oxidation state. Look at these group one elements, but they are in a plus one

6:57 oxidation state. These group elements are in a plus one oxidation state because they have one electron in their valence cell. So what oxidation state will they show? Plus one, then if lithium shows a plus one and two lithiums mean plus two, then overall neutral, that is, oxygen. Here, usually the oxygen oxide compounds that form there are minus two, so here too, but oxygen is minus two. When we look at peroxide, peroxide means O linkage, it has O2 minus and O O linkage, it is peroxo linkage. So when peroxide is forming, the oxidation state of oxygen is -1 and in the case of superoxide, the oxidation state of oxygen is -1. The state is minus half,

7:42 how do you calculate it, for example, let's say that the superoxide of potassium is ko2, but potassium is fixed at plus one, then you write this, plus one, there are two oxygens, 2 * x, assume that the overall is neutral, so zero, then x = -1/2, that is, the oxidation state of oxygen here is minus half, the oxidation number is there, later you will go to semester two, when you go there, you will see what different elements can show in the oxidation state, you will see these things about oxygen, so while you are here, keep this important point in mind that oxygen usually shows minus two, peroxide compounds there are minus one where peroxo linkages and linkages are found, and in the

8:29 case of super, it shows minus half, okay, well, in the reaction with water, MOH forms this type of hydroxide, the nature of hydroxide, we will see all those through a chart, these hydrides that we are seeing are reacting with hydrogen to form hydrides Lithium hydride, sodium hydride, potassium hydride, in this way, as we go down the group, the ionic character of these hydrides increases. Okay, from lithium hydride, the covalent character of lithium hydride is more covalent in nature, but as we go down the group, the ionic character increases. So, a

9:14 question may arise on this point. It reacts with halogen to form halides. So, we have seen some common points. The same thing. We will see these points from group two. And in group one, we have to keep in mind one more important thing. That's why I am saying this again and again. According to the question, we will revise those points once again. For example, let's say lithium reacts with nitrogen to form lithium nitride. Okay, then in group two, what we see is that in reaction with oxygen, this monoxide is formed and peroxide is formed. Barium strontium reacts with nitrogen to form nitrites. But the tendency of forming nitrites is down. The group, however, reacts

10:00 with water to form hydroxides, halogens, halides, hydrogens, and in this case, beryllium, magnesium, calcium, strontium, barium, magnesium, and the hydrides of beryllium are covalent in nature, so they exist in the form of polymers, such as BH2HNMGH2HN. In this way, the ionic character of the remaining hydrides increases, but they are covalent in nature, and in the

10:46 case of the remaining hydrides, the ionic character increases as we go down the group. Okay, let's say that here, instead of the metal, this hydroxide is formed. I haven't written beryllium here. If beryllium is beryllium hydroxide, the hydroxide of beryllium is amphiphilic in nature. Beryllium oxide is also bivalent in nature. Beryllium Beryllium oxide and hydroxide are bivalent in nature. Okay, let's move on to some important points. Through this chart, we will see first the degree of hydration.

11:32 If you ask us what the order of hydration is for these ions, generally the order of ionic radius is down the group. If we first talk about atomic radius, lithium, sodium, potassium, rubidium, cesium, then the atomic radius or the size of the atom is increasing down the group. Okay, if we talk about ionic radius, then in this case the ion will be formed in the plus one oxidation state, that is, lithium plus sodium plus potassium plus rubidium plus cesium plus down the group. This ionic radius is increasing. But if you are told that in aqueous solution or aqueous Li

12:17 plus In the case of aqueous, if we talk about ionic radius, then in that case we will see the opposite order, that is, if we ask about hydrated radius, after hydration, we will see that the radius is ionic radius, in that case the order is this, that means you have to see what is being asked in the question. The question can also come with hydration enthalpy. The smaller the size of the cation of an ion, the greater its hydration level will be, and hydration means that it is going into water. Being hydrated, the

13:03 energy it is releasing as a result of hydration is called hydration energy or enthalpy. So the smaller the size, the greater its hydration, the greater the degree of hydration, and the higher the degree of hydration, the higher its hydration enthalpy, and the higher the degree of hydration, that is, the more hydrated it can be. So the hydrated radius is the radius that it has after hydration, so since we generally see the order of their radii In that case, lithium is the smallest size cation, so we can write here lithium plus this cation's smallest size here is the smallest size small size because of that

13:51 its hydration level is higher because of that its hydration level is higher hydration level higher hydration level question can be asked about which one has higher hydration enthalpy same concept high hydration level means more energy is being released as a result of hydration i.e. hydration enthalpy is higher enthalpy then if hydration enthalpy is higher it means after hydration hydrated radius will be higher so in this case hydrated hydrated radius will be higher so whenever you are given a general order like this

14:36 or gaseous in that case you will say that ionic radius will increase down the group but whenever you give aqueous or talk about hydration then but the smaller the size of the small size cation the higher its hydration so its just opposite order can be seen here So a very important point that we have to keep in mind is that we will apply the same concept to Group 2 as well. So together we see here that as we go down the group, the hydration level increases. This is called the hydration level. From here you can ask about hydrated radii. The same concept is also seen here in the case of alkaline earth metals, as we go down the group, beryllium 2 plus. Since we are seeing

15:22 this here, we are seeing this in Group 2. Group 2 means NS 2 and this is we are seeing in Group 1. Group 1 means NS 1. That is why we will write 2 plus here. And the smaller the size, the smaller the size, beryllium 2 plus, then its hydration is higher. The hydration level is higher. So even if we say hydrated radii, we will get this order. Okay, what are we seeing in the case of hydroxides? As we go down the group, try to understand the group. Lithium, sodium, potassium, rubidium, cesium. These are Group one elements, when they form hydroxides, their alkalinity increases down the group because the cations that are metal and OH bond metal, when they come

16:07 down the group, what will be their size? Their size will increase. So, in the case of hydroxide, what we see is that this metal OH bond is getting weak and the bond is breaking easily, which means OH minus ion will be available easily and as a result, the alkalinity will increase. So, as you go down the group, you do n't have to memorize everything. You can keep it in mind with the concept of Down the Group. Meanwhile, whenever we come down the group, the alkalinity increases. Well, first let's look at these points. Thermal stability in the case of carbonates. In the case of carbonates, metal carbonates, which are seen in group one, their thermal

16:54 stability increases down the group and their solubility also increases. Stability and solubility in group one increases as we go down the group. The stability of sulfates in group one and the solubility of sulfates also increase as we go down the group. Density is a very important point. We will see these points again in the form of questions in many places. So when we answer them again, we will revise them once again. Density is a big question because the order of density that is seen here. See, density is equal to mass by volume. So as we go down the group, the atomic mass increases. Obviously, the density will increase.

17:40 But at one point, it is seen that after lithium, sodium, when we come to potassium, there is a much greater increase in atomic size. That is, the volume increases and the density is equal to mass by volume. So if the volume increases, the density will decrease. So here, here, we see a different trend. And where we will see a little exceptional behavior, an exceptional trend, that is where the question comes from. So lithium Sodium, potassium, rubidium, cesium, in the middle of this increase in sequence, we see that in the case of potassium, the

18:26 density is decreasing due to the increase in atomic volume, so it does not become liquid. Let's remember, lithium, sodium, potassium, which is not written, but write it down. Okay, not liquid. That is, after lithium, potassium, then sodium, sodium potassium. What we see is that the density of potassium is becoming less than that of sodium. Okay, this time, let's move on to Group Two. In the case of Group Two, what we see is that magnesium, calcium, strontium, barium, this is that the hydroxides of the elements of Group Two are increasing in their case as we go down the group. Similarly, we will see that the alkalinity is increasing. Okay, and in their case, the stability of carbonates is increasing down the group,

19:14 but the solubility is decreasing. Look, beryllium carbonate. Then when we go down the group to beryllium carbonate, the solubility decreases. In the case of sulfates, the thermal stability is increasing, the stability is increasing from beryllium to barium, but look at the solubility, it is decreasing, right, for example, beryllium sulfate, magnesium sulfate, soluble in water, calcium sulfate, slightly soluble, and the rest are almost insoluble, right, that means the solubility is decreasing, and in the case of density, we have to keep in mind the trend that we see here, what we see is beryllium, magnesium, calcium, in these cases, the density is decreasing, then see, beryllium has the most, and then,

20:00 if we arrange the whole, if we arrange the whole, who has the most, barium, then strontium, then we see beryllium, magnesium, calcium, so this order, this order, we have to keep in mind, these four, where there are quite a few important points, we saw together, more important points, I said on some previous pages, more important points, we will see, let's go through the questions, now let's go through what the first question says, see, it says which order is ionic Look carefully at the correct order of the radius. There is no aquas written here. It only talks about the ionic radius. And notice that lithium, sodium, beryllium,

20:45 magnesium. So group one and group two are combined. Now you understand the matter. Who is group one and group two? Let's write a little bit about lithium, sodium, and here we have beryllium and magnesium. Okay, if we talk about the order of ionic radius separately, then down the group is what it is? What is increase? Down the group is what it is? What is increase? Okay, and this is along the stage. You can understand that lithium, lithium, how much lithium is three, atomic number four, sodium in beryllium, how much sodium is 11, 12,

21:31 magnesium. So you have to master the periodic table very well. Only then will you be able to understand things easily. Look, going from lithium to beryllium, this means that we know that we are talking about ionic radius. Ionic radius or atomic radius or the size of the atom decreases as you go down the group from left to right along the period. So as you go down the group from left to right along the period, they decrease. They decrease. They decrease. And even then, you can understand by looking at them. What am I saying? Relate the things. Everything is taught. Sodium plus magnesium two plus sodium plus. That

22:17 means the number of protons here is 11. What is the number of protons here is 12. What is the number of electrons? Look, one electron has gone. It is 10. Two electrons have gone. It is 10. That means you understand. And isoelectronic species. The number of electrons is equal. Isoelectronic species. Remember, in the case of isoelectronic species, do we see how many protons it has? Where is the positive charge of the nucleus more? And in the case of cations, we could not say from there that the more positive charge there is in the cation, the greater its radius, the cationic radius or ionic radius decreases. So here we

23:02 see that this is also understood with the concept of isoelectronics or we say left to right whatever the same thing the concept is first so compared to this its cationic radius will be less that means that it means it is understood that with respect to group one the ionic radius of group two will be less it will be more than group one that means we have to put group one first we have to put group one first okay look this time look this time group two will be the least it will be last here but group one is there cancel here sodium plus magnesium two plus this order is ok there is nothing wrong with it but beryllium two

23:48 plus compared to that magnesium two plus do n't look check from order option I am saying slowly so that you can understand the question yourself because any example question can come in any way MCQ means not to fix anything so if you have the concept it will be correct then what is happening in magnesium two plus compared to beryllium two plus Increase is down the group, here it says decrease, you can see it here, there is a mistake here, there has been a mistake here before, there has been a mistake before, there has been a mistake in many ways, firstly it is written last, secondly it says sodium is decreasing compared to lithium, there are many mistakes in many ways, well come to this this time, magnesium is more than beryllium plus plus, it is okay,

24:34 it is okay, but look at this place, in the case of lithium plus sodium plus same group, the ion down the group will increase, here decrease says cancel cancel cancel then this is it Look at the equation, sodium plus, look at everything, you have to see it, not just by looking at the two, it is the same here, it is correct here, from beryllium to magnesium to plus, it increases, and sodium plus is more with magnesium to plus, that is also correct. He tells us to arrange the four of us together, between sodium and lithium, sodium plus is more than lithium plus, that is also correct and overall this entire order is correct, you will not be able to match your concept with any of the other orders, option D

25:20 is correct, how is it done? I am saying again, down in group one, the group increases, look at it like this individually, down in group one, the group increases, then from lithium to sodium, down in group two, the group increases, beryllium to magnesium increases, and whenever we go from group one to group two, it decreases with respect to group one, group two, The decrease is correct. I looked at it separately and looked at the groups one after the other. According to the period, it is correct. Look, a nice question has come up. What is the order of hydration enthalpy of alkali metals? What did I just say? The smaller the size of the cation, the higher its hydration level, which means

26:06 its hydration enthalpy is higher. So you say that here lithium plus will be the most. Alkali metals: lithium, sodium, potassium, rubidium, cesium. Lithium plus will be more. Lithium plus will be more. Then sodium potassium, rubidium, cesium, sodium potassium. Here, cesium has been brought in the middle again. So none of these happened. Here, lithium, sodium potassium, rubidium, cesium, down the group, the hydration enthalpy is decreasing because the size of the cation is increasing. The larger the size of the cation, the lower its hydration enthalpy will be. So option D is correct here. See which one? The density of the element is in the order of lowest density. We have seen that lithium, sodium, potassium, rubidium,

26:53 cesium are down the group elements. I have written them side by side. But are they actually down the group elements in group one? We have seen an exception here that after lithium, when we go from sodium to potassium, the density of potassium is less than that of sodium. The rest is increasing as it increases. But we have to keep in mind that lithium is not given in the option because if lithium is not given, the density of lithium is the lowest. It is correct that the remaining four are given. That means that potassium will be the lowest in this case. Option B is correct. So, the question must be

27:40 practiced. And every time you revise this chapter, it is very good, but you must ask the question. It is very important to see whether you can do the question yourself or not. There is no math in this chapter. There is no room for thinking. You have to know how to think about things with concepts. You can, but of course you have to think about it with a concept where the rest of the thinking comes directly. Some questions that you have to know are asking you what is the formula of plaster of Paris. You have to know that. You ca n't solve it even if you think a lot. Unless you have ever read it. So, reading and questioning atoms, whether I can do it on my own, whether I can apply what I have read, that is very important. Which

28:31 one has the lowest melting point. This is the concept of melting point. Look at this same concept of things. You have read about chemical bonds where we have seen how the melting point is called. Remember what we said that the melting point is inversely proportional to the covalent character. The more the covalent character, the lower the melting point. All of these are chlorides. So here, the cations are Na plus Li plus K plus Cesium plus We know that the smaller the size of the cation, the smaller the cation. The

29:19 smaller the size of the cation, the smaller the size, the greater its covalent character, the greater its covalent character. Okay, so the smallest size cation here is lithium plus, so its covalent character is greater. That means that the corresponding compound given here is halide chloride, its covalent character is greater. The higher the melting point, the lower the melting point, so it says the lowest. So, L ICL is the correct cation. When we talk about the rule of any covalent character with cations, when we talk about the development of covalent character, the development of covalent character of ionic compounds, what do we see there? The smaller the size of the cation, the

30:06 greater the charge of the cation, the greater its covalent character. And if we look at it with anions, we will see that the larger the size of the anion, the greater the charge. There is no need to look at the anion here. The anion is fixed. There is nothing to say about the charge of the cation because the charge of all is plus one because they are group one. Element but there we compare the size and see lithium plus the smallest size cation small size cation means its polarizing power is more exactly these are important concepts of chemical bonding they are being revised polarizing power the higher the polarizing power of the cation means in that case the more covalent

30:54 character will develop in this compound the more the melting point the lower the minimum wanted to know here the next question says what will be produced as the main oxide when lithium sodium potassium is burned in the presence of excess air I first said that in group one lithium is usually produced as the main oxide the common oxide or monoxide of lithium this is li2 in the case of lithium li2 in the case of sodium peroxide na2o2 and in the case of potassium superoxide very important you see how the question comes li2 li2 li2 li2 a2 Ketu Option D Correct L I To N Ketu Already Today I have told you a while ago about the oxidation

31:42 number of oxygen, what will happen in which case? Okay, let's take a look again. It says which salt produces a yellowish-golden flame in the flame test. The chloride salt that the salt gives here is sodium, potassium, lithium, rubidium. So let's write a little bit here about the flame test. The flame test does not say that it is a flame test. Through the colors that are seen in the flame test, we can identify which element is present there. So here we will see that yellow is golden. In each case, if I write a little bit, look at the colors of the flame test for lithium, not dark red. Lithium, sodium, potassium,

32:30 rubidium, cesium. Look at the colors of the flame test for each. Look at the colors of the flame test. In the case of lithium, it is dark red. In the case of sodium, it is golden yellow, that is, golden yellow or this yellowish golden. Okay, what will we see in the case of potassium, what will we see in the case of purple, what will we see in the case of rubidium, what will we see in the case of reddish purple? I am just showing these in other colors. The exact color cannot be shown here because then many colors will be mixed with the board and it will not be understood. All the colors are just

33:17 written like this to explain. Okay, and in the case of cesium, I did not show any of the blue colors, but I just tried to show different colors. Only the golden yellow matches the sodium color. Anyway, the colors that we see in the flame test have to be kept in mind. The direct question comes from there. Here, we are talking about golden yellow or yellow. Abu Sonali, then in which case will it be? Where there is sodium, then it will become NaCl. Correct. Let's move on to the next question. It says that if gypsum is heated to 390 Kelvin, what is produced? The first option in the four options that did not give calcium sulfate. Dot to H.

34:03 This is gypsum. This is gypsum. If it is heated, 390 Kelvin temperature which says or you have 110 degrees to 120 degrees Celsius temperature here but you have to keep in mind yes in the case of plaster of Paris preparation we do not increase the temperature too much than 120 degrees in this reaction and here from here we get plaster of Paris which is two CsO4 H2 to balance this we are taking this here two and in that case look here two calcium sulfate has become two two four molecules of water

34:49 here already one molecule is this but dot H it is just two Cs four plus three H and this what is being formed is plaster of Paris plaster of Paris so this is plaster of Paris but look at the option in the option but you do n't have it written like this so how can this be written this is this we can write this this is this two Cs four this caso4 dot this H2 this since I did caso4 so I will make it half H2 So we can represent it this way too. So which option is correct here is ca S four dot half H two. Okay, plaster of Paris is produced. The

35:35 next question is related to dead burn plaster. Dead burn plaster. Look at which one. Whenever we get this plaster of Paris, when it is heated again at a temperature of 200 degrees, what will we get? We will get anhydrous calcium sulfate. Dead burn plaster is anhydrous calcium sulfate where there are no water molecules. So this calcium sulfate is just written caso4. This is option B which is called dead burn plaster. Super burnt plaster is also called super burnt plaster. Okay, so these are the little things. This

36:20 information needs to be kept in mind. Okay, look at the next one. It says which of the following alkaline earth metal sulfates is the most soluble in water. In terms of solubility, we see that beryllium, magnesium, calcium, trontium, and beryllium. Down the group solubility but decreases Down the group solubility is decreasing Beryllium Magnesium is well soluble Calcium sulfate but less soluble Less soluble and then it becomes almost insoluble So then it is more

37:06 soluble Here is beryllium or magnesium Here is option D Correct Solubility is decreasing Okay I have given the related chart of this topic first Take a look and see what the next one says Look the next one says Which of the following alkaline earth metals and carbonates has the lowest thermal stability Metal carbonate As carbonates Group two elements give us alkaline earth metal carbonates So here here we will see Beryllium Magnesium Calcium Trisium Barium Down the group Thermal

37:54 stability is increasing Thermal stability is increasing Solubility is decreasing Thermal stability is increasing Let me show you the chart once again Look, this was our table where we see that the solubility of beryllium to beryllium decreases in carbonate, here the solubility of sulfate decreases in thermal stability but increases in thermal stability. Okay, some important points that I keep saying over and over again, if you make a chart like this and look at it a few times, you will remember that the thermal stability increases down the group. Here, they are asking us which is the lowest. So, in whose case is it the lowest? We will see in the case of beryllium carbonate. So, option D is correct.

38:41 Let's move on to the next question. Which of the given elements shows an angular relationship with magnesium? First, I said lithium. Here is sodium. Here is beryllium. Here is magnesium. The two elements located at the corners are lithium and magnesium. There is a diagonal relationship or angular relationship between them. So lithium shows an angular relationship with magnesium. Look at the next one. Good question. Why is it a good question? The same thing, but here group one and group two have been combined. Beryllium. Magnesium, barium, these three are in group two, their sulfate and with it, sodium is given here, that is, it is the element of group one, its sulfate,

39:32 what do we see in terms of solubility of these four, that in group two, the solubility is decreasing down the group, I immediately saw that I also showed that the solubility is decreasing down the group, that means barium will be the least, beryllium, then magnesium, then barium, well, in all cases, barium is last, you understand, now sodium sulfate, which is a sulfate of group one, group one alkali metal sulfate, compared to that, the solubility of alkaline earth metal sulfate is less, so who will be first, group one, then where is Na2S4 first, here, then beryllium, magnesium, beryllium, the solubility is decreasing, so group one and group two are compared here, a

40:17 very important point, group two has less solubility than group one It will be in the case of sulfate, so option A is correct here. Okay, look at the next question. Does it say that lithium is produced by reacting with air? It says reaction with air. So whenever we talk about reaction with air, we will look at the reaction with these two. So lithium reacts with air to form lithium monoxide, which means lithium monoxide, and reacts with nitrogen to form lithium nitride. Here,

41:06 we have looked at the reaction of the monoxide. Today, we have looked at the nitride reaction first. Let's look at the reaction of lithium plus N to form lithium nitride. To balance, we have given six here and two here. Then the balance is done. Okay, some more important points in this context. I will say that a question comes from nitrate. The question that comes from nitrate. Look at this group one element here. Everyone, I am writing on the next page. First, let's complete this question. Li2 and Li3N. Option A is correct, there is an important point, Mn3 forms this type of nitrate, group one element is correct, and

41:52 all these nitrates decompose under the influence of heat to form Mn2 plus O2, to balance them, here are two, here are two, two, four, five, six, here are six, oxygen is balanced, that means the nitrates of group one decompose and produce nitrite and oxygen in heat, but here is very important, questions have repeatedly come from this place in various exams that lithium nitrate produces lithium monoxide plus NO2 plus O2 due to thermal decomposition, the rest are according to this, so if you are told that nano3 and li are elements of the same group, their nitrates are also their own, so wo n't both produce Mn2 type nitrite? In the

42:40 case of lithium nitrate, lithium monoxide plus nitrogen dioxide is produced, and in the case of nano3, normally we get sodium nitrite plus oxygen, balance it here. To balance here, put four here, put two here, put two here, look at oxygen, three four 12 here two two four and well here you have to do four here four two eight nine ten 11 12 so you can do the balance because you will not be allowed to write anywhere but you have to keep in mind what is being formed very important here but these two are being formed and here according to normal reaction what happens in the rest is happening in this case you have to keep in mind okay so next question come on let's see what the next question

43:28 says next question says metal hydrides are ionic covalent or molecular in nature lithium sodium potassium rubidium cesium arrange the compounds in ascending order of ionic character I also said the question look carefully what I am saying comes from all those important places again and again question this way you will create the chapter through your questions but of course after revision once you can do the question yourself and it will be convenient see down the group what we are saying ionic character is increasing As we go from lithium hydride to lithium hydride, the covalent nature of hydride increases down the group, which means lithium

44:14 will be the lowest, then sodium, potassium, rubidium, cesium. Option B is correct. The next question says which of the following alkali metals has the lowest melting point and can melt when the ambient temperature is 30 degrees. In the case of alkali metals, we see that lithium, sodium, sodium, potassium, rubidium, cesium, as we go down the group, their melting point decreases and in the case of cesium, it is 302 Kelvin. If we say that 30 degrees means 30 degrees, you can understand. Add 273. What does 30 degrees mean? 30 degrees means 303 Kelvin. So you

45:01 can understand that which can melt when the ambient temperature is close to 30 degrees. That is cesium. Okay, the next question is similar in concept. Okay, calcium. The correct order of ionic character of the hydrides of beryllium barium is an important point. Write down a small thing. Calcium hydride is called hydrolith. It is called hydrolith. Now the ionic character. I have already said that hydrides of beryllium and magnesium are in the form of covalent polymers. In the case of the rest, the ionic character of hydrides will increase down the group. So here beryllium has also been given a question. Beryllium magnesium is not written all, I am

45:47 writing to those who have it. Calcium will be last. Beryllium hydride is covalent in nature. This is covalent nature. But what does ionic character mean? Down the group, the ionic character is increasing. So, the most is H2, then the most is calcium. The hydride of beryllium is the least. Option C is correct. Here it says which order is correct in terms of solubility in water. The solubility is given here. The sulfate of group two elements. The solubility decreases down the group. So we will see that beryllium Magnesium then calcium then strontium then barium option B is correct decreasing

46:33 this is decreasing look at the next question says in the flame test of alkaline earth metal salts with Bunsen burner determine the correct compatibility of the salts related to the flame color from the given options so here in the case of calcium strontium and barium we will see what is the color of their flame test in the case of calcium strontium and barium brick red color brick red color then one p one p is in these two options cancel the rest strontium is car red which is crimson red color it is brick red it is

47:18 crimson red strontium two r two r it gave two q two r option a correct in the case of barium barium it is green apple color ok green like apple green like young apple green color so is this c q or not three q option a correct and see through the question its flame test We revised the colors, let's move on to the next one. The next question says, "Very important." Yes, in which physical state does D-Cl2 exist in this form? It is a polymer form. This form is given. This is the polymer form where B-Cl2

48:04 exists as a whole N and it exists in the solid state. In the solid state, it exists in the polymer form. In the vapor state, it exists as a dimer and monomer. In the vapor state, it exists as a monomer and as a dimer. When monomer is present, B-Cl2 is a dimer. When B-Cl2 is a dimer, it exists as a monomer.

48:53 When B-Cl2 is in the vapor state, we see that B- Cl2 exists as a dimer, and in the solid state, B-Cl2 exists as a polymer. So, this form that the polymer form has given us is B-Cl2 is a monomer at high temperatures. The two vapor states are written together. I also specifically said that when the dimer and polymer in the vapor state are in a physical state, it is in a solid state, then option C [Music] is correct. Let's move on to the next question. When a hydrated compound is heated, the monohydrate compound Y is obtained. When

49:40 X is heated above 373 Kelvin, a dry white powder is produced. X and Y are the options respectively. Look at baking soda. Washing soda. Soda ash. Dead burn plaster. These are given. Look at washing soda. Cloth. Raw soda. This is na2co3. 10h2o. Okay, this is decahydrate. Decahydrate. Because there are 10 molecules of water here. When we heat it to 100 degrees Celsius, no na2co3. dot H. Two plus nine molecules of water come out. That means this is X. This is Y. Which has one molecule of

50:26 water. That is, this is Monohydrate is formed. This is a reaction of washing soda. This is an important reaction from which the question comes. If you understand, after heating washing soda where there are 10 molecules of water, what do we get? Na2CO3H2, that is, monohydrate. It is heated again. It is heated again. Give it a higher temperature of 100 degrees Celsius, which is above 373 Kelvin temperature. Then anhydrous sodium carbonate is formed from here. If anhydrous sodium carbonate is formed, then this is Na2CO3, where there are no molecules of water. Anhydrous. It is called soda ash. Soda ash is okay

51:12 or soda ash is called. Then this is washing soda. Soda is soda ash washing soda and soda ash because it is anhydrous white powder it is anhydrous what it says is soda ash soda ash and y is y is monohydrate this and x which is x and y okay wait a minute here here monohydrate here y is said but in the option but it is not given anywhere washing powder will be x so cancel these two options first and dead burn plaster is not here dead burn plaster is in calcium sulphate so the question will be corrected a little bit you have to write in the question that x is this washing soda and with it this anhydrous white powder

51:59 you make it z and here this no this has to be z this has to be framed like this otherwise option will not match okay somewhere monohydrate is not written anywhere anhydrous sodium carbonate is called soda ash okay option b correct okay look at the next question it says sodium pump is an important system in the body of animals where is any ion in biological function The related question is asking here, what else is needed in this pump besides the Na+ ion? Everyone knows that it is a sodium potassium pump. So here, besides the Na+ ion, which potassium plus is needed? The next question is,

52:45 which of the following sulfate salts has a higher hydration enthalpy than the lattice enthalpy? Look, if the hydration enthalpy is higher than the lattice enthalpy, then its solubility in water is higher, which means it will dissolve well in water because the hydration enthalpy is higher. And the sulfates of the elements of group two, which we have seen, decrease in solubility down the group. Beryllium magnesium sulfate, where there is beryllium sulfate, of course, in this case, the hydration enthalpy value is higher. The answer will be related to solubility. Option B. That's why the concept is important. They didn't tell you about solubility. They told you where the hydration enthalpy value is higher, which is where the dissolution is happening. It is easy to answer the question

53:32 according to the option Beryllium sulfate. Again, this type of question is a biological question. Which one is the cofactor of the enzyme used in the transfer of phosphate from ATP to ATP? Magnesium is present as a cofactor in the transfer of phosphate from ATP. Okay, so here magnesium will be option B. The next question says what is the aqueous solution of lime called? Look, lime, which is calcium hydroxide, calcium hydroxide, when it is in a little water, it is clear, that is, a thin, that is, an aqueous solution that is clear, that is, which is

54:18 called lime water, lime water. But when we are talking about this aqueous solution, that is, whenever calcium hydroxide is dissolved in a large amount of water, in that case, that white, that is, a milky suspension is formed, which is called milk of lime, which is called milk of lime. So the aqueous solution that we are talking about is which one is quick lime? Lime is a powder of lime, calcium oxide is milk of lime, aqueous solution is happening, this is right, aqueous solution is happening, option C is now some more points from this place which you have already read in many places before, for example, suppose that

55:05 the clear solution of calcium hydroxide, polylime, aqueous solution, whenever carbon dioxide is being passed there, calcium carbonate is being formed there, which is precipitating, therefore the clear solution becomes cloudy there, calcium carbonate plus H2 is right, then again, then this calcium carbonate and H2 are formed, if more carbon dioxide is passed here, then soluble calcium bicarbonate is formed, so the cloudy lime water becomes clear again, take a look at the balance, hydrogen two oxygen is three four five six three two six okay, so

55:50 it is soluble, from these, be it statement based question or reaction based question, MCQ, so important place can come Washing soda Washing soda We have read that washing soda is na2co310h2o Option D creates a golden flame Who is sodium Potassium We have seen purple Calcium is brick red Barium We have seen green Apple color In which of the following methods is NaOH prepared? Look Castner Kellner cell Sodium hydroxide is prepared through electrolysis The name of that method is Solvay method Which is prepared in Solvay

56:37 method Washing soda is prepared in clothes Raw soda and glass Kellner cell Sodium hydroxide is prepared through this This time I will tell you something more Our question is through practice questions We have done many important places First of all I said that this chapter is prepared in a different way because everyone's speech is the same Ma'am I am forgetting how to do so many reactions That is why I will tell you that the batch that was there before Abhiyan Bangla is 2

57:24 There you are getting full revision from there you are in two lectures You can prepare the S block and with it, the class that is in today's class, the class that is in the 2nd expedition, practice these MCQs from the class that I gave today, okay, and then try to ask some more questions yourself. I hope that after doing these, you will be able to do these questions on your own. In this chapter, there are some information-

58:10 based direct questions that we have seen. So you have to read and memorize the concepts everywhere. Why is it not necessary? Remember them with the concepts. And if you read them, you will remember them. And if you practice them, okay, let's go to today's class. Stay well, stay healthy, see you in the next class. Thank you.