English Medium Class 10 - CBSE Question Bank Solutions for Science

Ferrous sulphate decomposes with the evolution of a gas having a characteristic smell of burning sulphur. Write the chemical reaction involved and identify the type of reaction.

Why do fire flies glow at night ?

A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved.

Write a balanced chemical equation of the following reaction and also classify them.

Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution.

Write a balanced chemical equation of the following reaction and also classify them.

A piece of sodium metal is added to absolute ethanol to form sodium ethoxide and hydrogen gas.

Write a balanced chemical equation of the following reaction and also classify them.

 Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide gas.

Write a balanced chemical equation of the following reaction and also classify them.

Hydrogen sulphide gas reacts with oxygen gas to form solid sulphur and liquid water.

A magnesium ribbon is burnt in oxygen to give a white compound ‘X’ accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound ‘Y’.

1. Write the chemical formulae of X and Y.
2. Write a balanced chemical equations when X and Y are dissolved in water.

What happens when a piece of

1. zinc metal is added to copper sulphate solution?
2. aluminium metal is added to dilute hydrochloric acid?
3.  silver metal is added to copper sulphate solution?

Also write the balanced chemical equation if the reaction occurs.

What happens when

1. ZnCO₃ is heated in the absence of oxygen?
2. a mixture of Cu₂O and Cu₂S is heated?

A non-metal A which is the largest constituent of air, when heated with H₂ in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.

1. Identify A, B, C and D
2. To which group of periodic table does this non-metal belong?

According to the evolutionary theory, formation of a new species is generally due to

From the list given below, select the character which can be acquired but not inherited

Which of the following statement is correct?

Draw ray diagram showing myopic eye.

A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.

A person needs a lens of power –4.5 D for correction of her vision.

1. What kind of defect in vision is she suffering from?
2. What is the focal length of the corrective lens?
3. What is the nature of the corrective lens?