Class 10 CBSE: 20 MCQs You CAN'T Miss Before Boards! | Full Revision

[00:00:02]Hello future toppers. Welcome to the channel to our brand new grade 10 MCQ master series. If you are aiming to ace your science board exams, you are in the exact right place. Today we are going to start with chapter one chemical reactions and equations. Chemistry can feel a bit tricky but the best way to master it and score full marks is by practicing the right multiplechoice questions. In this series, we are going to break down the most frequently asked exam questions. So, clear your doubts and show you exactly how to support the correct answers in seconds. So, grab your pen and notebook, test your knowledge, and let's make chemistry super easy together. If you're excited, hit the like button, subscribe to the channel so you don't miss any future videos. Let's get started. Let's start with the first question.

[00:01:00]So there is the equation given to you.

[00:01:03]Silver nitrate and sodium chloride reacts to form sodium nitrate and silver chloride. In the second reaction it's given potassium sulfate and berium chloride which gives berium sulfate and potassium chloride. So there are some options given to you that on the basis of these options you have to choose the correct option. Okay. Which of the following options clearly describes both the reactions. One is double displacement. Second is displacement reaction.

[00:01:37]Both one and two are displacement and precipitation reactions. Both one and two are displacement reactions and precipitation reactions. One is displacement and two is double displacement reactions. You clearly know that in the first reaction there are white PPTs formed of AgCl that is of silver chloride right and in second one also white PPS like white precipitates white insoluble precipitates of berium sulfate are formed and also the exchange of ions also taken place there. So option number C both one and two are double displacement reactions and precipitation reactions. C option is absolutely correct.

[00:02:17]Let's move to the next question.

[00:02:20]The gases evolved on heating lead to nitrate crystals are which are the gases on heating lead nitrate crystals are obtained. We know that when PBNO3 twice that is lead nitrate heated up then it decomposed into three main products that is lead oxide we can balance also like four 2 and two here. So the products NO2 and O2 which are in the option D option. So D is our correct option.

[00:03:05]Okay.

[00:03:07]Next third one. The correct balanced chemical equation showing exothermic reaction in which natural gas burns in air. Natural gas. So you should know what is natural gas. You know already that is CH4.

[00:03:21]And in all the option CH4 is given to you. So no need to worry. But in case the teacher want to test you, he or she can give you alternatives like uh in one reaction it is given that CH4 in another reaction he or she can give you carbon and student mostly get confused between methane and CH4 and that carbon carbon meant for coal. Okay.

[00:03:48]So which is the balanced chemical equation here?

[00:03:54]Yes. So option number two is absolutely correct. Let's move to the next question. Which of the following are combination reactions? You know what are combination reactions?

[00:04:04]When two or more reactants combine to form single product is known as combination reaction. And you can clearly see that in second and in third part magnesium oxide and water when they react each other then we are getting magnesium hydroxide single product in case of aluminium and oxygen when they react together we get aluminium oxide. So second and third is correct. So overall D option is our correct answer. Done.

[00:04:50]Next.

[00:04:53]to a small amount of copper oxide in a beaker when we add dilute hydrochloric acid slowly with stirring the change in color of the solution due to formation of.

[00:05:04]So the question is amount of copper oxide is given in your beaker and dilute HCl dilute hydrochloric acid add constantly stir. Okay. When we mix it up then what will be the change in the color of solution and it is due to the formation of which is the correct option? Copper oxide which is black in color. No. Copper chloride which is blue in color. No.

[00:05:33]Copper chloride which is green color.

[00:05:34]Yes. Copper oxide which is black in color. It is absolutely wrong. So option number C is absolutely correct. Okay.

[00:05:42]Done.

[00:05:46]Sixth one. It's very easy. The following equation X KI plus H2O2 gives I2 + Y KO.

[00:05:57]Potassium iodide when reacts with H2O2 it gives iodine and potassium hydroxide. Yes. So which cofficients will balance the above equation.

[00:06:11]You can do by option also. Okay.

[00:06:16]If I write two here and two here how many potassium are there on both sides?

[00:06:21]Two oxygen are also two hydrogen are absolutely correct. A option is absolutely correct here. Done.

[00:06:29]Then the seventh one. Which of the following is an example of displacement reaction? Very important. Which of the following is an example of displacement reaction? Clearly you can see the combustion of natural gas.

[00:06:43]Is it true? Is it the example of displacement reaction? No.

[00:06:49]The reaction of reactive metal with a dilute acid.

[00:06:55]The reaction yes like Zn plus HCl it gives Zn Cl2 plus H2 gas. This is the displacement reaction. Right? We can check other options. Electrolysis of water.

[00:07:21]This is the decomposition reaction of quick lime with water.

[00:07:30]No.

[00:07:32]So our correct answer is option number B. Right.

[00:07:38]Next is eighth question. Very very important. The volume ratio of the hydrogen and oxygen gases liberated during the electrolysis of water.

[00:07:52]You can clearly see that water decomposes into two products that is hydrogen gas and oxygen gas. Right?

[00:08:03]After balancing what we will get two moles of hydrogen and 1 mole of oxygen.

[00:08:23]So the ratio is 2 is to 1. 2 moles of hydrogen and 1 mole of oxygen. The ratio is 2 1. Option number B is absolutely correct.

[00:08:32]Next is C6 H1206. What is this? This is glucose.

[00:08:40]Remember this formula. This reaction is very important.

[00:08:44]Glucose when reacted with oxygen, it gives carbon dioxide and water. Which type of reaction is this? Displacement reaction? No. Endothermic? No.

[00:08:54]Exothermic? Yes. Heat is absolutely released here. Exothermic reaction.

[00:08:59]Neutralization? No. At any cost? No. No.

[00:09:01]No C option is absolutely correct.

[00:09:05]These are very important questions from the board exam point of view.

[00:09:10]You can say these are the golden MCQs of the chapter. Okay. Next 10th question.

[00:09:15]Assertion reason.

[00:09:17]Reaction of quick lime with water is the exothermic reaction.

[00:09:22]Absolutely. Quick line is Cao calcium oxide. When it reacts with water, what does it give?

[00:09:31]Ca twice. What is Ca twice?

[00:09:37]Its common name is leg line. And what is its chemical name?

[00:09:47]Calcium hydroxide. Yes, very good.

[00:09:51]Large amount of heat is evolved on the reaction of quick lime and water. Yes, absolutely.

[00:09:57]Absolutely correct.

[00:09:59]Both are the statements correct and reason is correct explanation of assertion. Large amount of heat is evolved. It indicates that it's a exothermic reaction. So reason is correct explanation of assertion. So uh here B option the options are twisted here. R is not the explanation of A is in A part and it's in B part. Correct explanation of A. 90% of the students will going to be wrong in this question due to the interchange of options. Be careful.

[00:10:32]Okay.

[00:10:34]Next 11th one. Which of the following is not an exothermic reaction?

[00:10:39]Which of the following is not an exothermic reaction?

[00:10:45]11th one.

[00:10:49]This is exothermic reaction of water with quick line. This is also exothermic respiration process. Exothermic.

[00:11:00]We are left with the last option.

[00:11:02]Decomposition of calcium. Yes, absolutely.

[00:11:08]Calcium oxide plus carbon dioxide. Okay.

[00:11:11]And this is endothermic.

[00:11:15]So option number D is our correct answer.

[00:11:18]Next question.

[00:11:20]The product formed when aluminium and magnesium are burnt in presence of air respectively are yes aluminium what is equalency + 3 minus 2 Al23. Some student don't know how to make formulas. Please revise the chart from your grade nine atoms and molecules chapter ions. You should know the charges on some ions and like sulfate ion, nitrate 1 to 20 elements you must know in series so that you can calculate the valency very easily in exam. Okay.

[00:12:02]Al23 what about this magnesium oxide? So Al23 magnesium B option is absolutely correct.

[00:12:13]Next is consider the following chemical equation.

[00:12:17]Yes, balance it. This kind of question we have done before also. Huh? I think sixth or seventh question we had done.

[00:12:25]Sixth question.

[00:12:27]The answer of this question you have to put in the comment box. Okay.

[00:12:32]14th one. In which one of the following situations the chemical reaction does not take does not occur? Milk is left open at room temperature during summer.

[00:12:42]Yes, it's absolutely correct.

[00:12:47]This is a chemical reaction. What does it happen here?

[00:12:53]You know bacteria converts.

[00:12:58]This is a chemical reaction. And what what is happening here? You can note it down.

[00:13:04]Sugar into lactic acid.

[00:13:10]Grapes get fermented.

[00:13:12]Yes, this is also a chemical reaction.

[00:13:16]Iron nail is left exposed to humid temperature. Yes, absolutely correct.

[00:13:22]This is also a chemical reaction.

[00:13:26]Iron reacts with oxygen and moisture to form rust which is also rust is also known as hydrated iron oxide. Okay, hydrated iron oxide. Last option is melting of glaciers. That is not a chemical reaction. Okay.

[00:13:57]Next is the main observations while performing the experiment of burning magnesium ribbon. What are the main observations? Magnesium ribbon burns with dazzling white flame. All the students know that. Absolutely correct.

[00:14:11]White powder is formed. Yes. Mg when mg and O2 magnesium and oxygen react they form magnesium oxide. Magnesium ribbon vaporizes. No, it never happens.

[00:14:24]Aqua solution of white powder turns blue litmus red. No. Magnesium oxide is basic in nature. So it turns red litmus blue instead of turning blue litmus red.

[00:14:34]Okay.

[00:14:36]So this is also wrong. This is also one and two are only correct options.

[00:14:42]C option is absolutely correct. Next assertion reason.

[00:14:47]Silver chloride turns gray in sunlight.

[00:14:50]Which type of reaction is this? Can anyone tell this?

[00:15:00]Yeah, it's a decomposition.

[00:15:05]Photoolytic decomposition. And what is its application?

[00:15:10]It is used in black and white photography.

[00:15:21]Decomposition of silver chloride into silver and green takes place by sunlight. Yeah, it's also true.

[00:15:34]AgCl it decomposes into silver and chlorine gas.

[00:15:46]Now it's balanced.

[00:15:48]Done.

[00:15:55]So both are true and R is correct.

[00:15:56]Explanation of A. A option is absolutely correct. 17th is also the same question.

[00:16:02]Yeah. 18th question. Very important.

[00:16:07]This is a good level of question.

[00:16:08]Everyone must attempt this. 18th question. In the following experimental setup, electrolysis of water. P and Q are the gases collected in the test tubes enclosing the electrodes R and S.

[00:16:22]Then select the options in which the matching is correct.

[00:16:29]Select the correct option.

[00:16:31]P is oxygen gas where P on P electro there is oxygen gas. No.

[00:16:43]Second on P hydrogen gas is collected.

[00:16:54]Is it true?

[00:16:57]Yeah, it's true. And R is cathode. That is absolutely true. Good. Q is hydrogen gas. No. On PB I have identified already. This is not the option.

[00:17:11]Second is absolutely correct. On Q on Q electro oxygen gas accumulated yes and S is a node. Yes, absolutely correct.

[00:17:20]So second and fourth option is absolutely correct. E option is our answer.

[00:17:26]Select from the following a statement which is not true about the burning of magnesium. Already we had done it burns with a dazzling white flame. It's true.

[00:17:35]They have asked not true. Okay. A white powder is formed on burning. It is also true. We have to check the false statement from here. It is an endothermic reaction. It is an example of combination reaction. Endothermic is absolutely correct. Here in the following case, the combination reaction occurs in.

[00:17:57]Yes.

[00:18:00]Here Cu plus H2O. Yes.

[00:18:06]Zinc plus carbon dioxide Na plus O2. It gives Na2. Yes.

[00:18:21]So, which of the following is a combination? Only third one. Can you identify other types of reactions here?

[00:18:29]First one is displacement.

[00:18:34]What about the second one?

[00:18:40]Displacement reaction. This is a combination in which two reactants combining to form a single product.

[00:18:49]What about the fourth one?

[00:18:53]Yeah, this is a combustion we can say or oxidation reaction.

[00:19:03]So what is the correct option here? Only three. A option is correct. Done. So all about today. I hope you have understood and uh a good level of questions you have practiced today. Repeat these questions and I hope you will get these type of questions in your upcoming exams in school and board exams. For more videos subscribe my channel. Like, comment and share. Thank you very much.