English Medium इयत्ता १० - CBSE Question Bank Solutions for Science

You are given the solution of lead nitrate. In order to obtain a yellow precipitate you should mix with it a solution of ______.

An acid which can decolourise purple coloured potassium permanganate solution is ______.

The chemical reaction between two substances is characterised by a change in colour from orange to green. These two substances are most likely to be ______.

The chemical reaction between quicklime and water is characterised by ______.

Which of the following is not an endothermic reaction?

One of the following is an exothermic reaction. This is:

The chemical equations are balanced to satisfy one of the following laws in chemical reactions. This law is known as:

When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution.

1. What do you think substance X is likely to be?
2. Name the substance which the yellow solid consists of.
3. Which characteristic of chemical reactions is illustrated by this example?
4. Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.

One of the following is not an organic acid. This is:

When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.

1. What could be solid X? Write its chemical formula.
2. What could be product Y? Write its chemical formula.
3. What is the common name of the solution of Y which is used for testing carbon dioxide gas?
4. Write chemical equation of the reaction which takes place on adding water to solid X.
5. Which characteristic of chemical reactions is illustrated by this example?

When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.

1. Name any two metals which can behave like metal X.
2. Name any two acids which can behave like acid Y.
3. Name the gas Z.
4. Is the gas Z lighter than or heavier than air?
5. Is the reaction between metal X and dilute acid Y exothermic or endothermic?
6. By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.

A metal X forms a salt XSO₄. The salt XSO₄ forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wires and alloys like brass.

1. What do you think metal X could be?
2. Write the name, formula and colour of salt XSO₄.
3. What is the blue precipitate Y?
4. Write a chemical equation of the reaction which takes place when salt XSO₄ reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

1. What is metal M?
2. What is solution S? Is it acidic or alkaline?
3. What is gas G?
4. Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
5. Is this reaction exothermic or endothermic?

The indicator which produces a pink colour in an alkaline solution is ______.

When a mixture of gases X and Y is compressed to 300 atm pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300°C), then an organic compound Z having the molecular formula CH₄O is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.

1. What are X, Y and Z?
2. Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.

When a piece of limestone reacts with dilute HCl, a gas X is produced. When gas X is passed through lime water then a white precipitate Y is formed. On passing excess of gas X, the white precipitate dissolves forming a soluble compound Z.

1. What are X, Y and Z?
2. Write equations for the reactions which take place:
   1. When limestone reacts with dilute HCl.
   2. When gas X reacts with lime water to form white precipitate Y.
   3. When excess of gas X dissolves white precipitate Y to form a soluble compound Z.

Name the various types of chemical reactions.

A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns reddish-brown. On rinsing the shirt with plenty of water, the reddish-brown stain turns yellow again.

1. Name the natural indicator present in curry stain.
2. Explain the changes in colour of this indicator which take place during washing and rinsing the shirt.
3. What is the nature of soap (acidic/basic) as shown by the indicator present in curry stain?

A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns reddish-brown. On rinsing the shirt with plenty of water, the reddish-brown stain turns yellow again.

Explain the changes in colour of this indicator which take place during washing and rinsing the shirt.

A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns reddish-brown. On rinsing the shirt with plenty of water, the reddish-brown stain turns yellow again.