English Medium इयत्ता १० - CBSE Important Questions for Science

Define ‘redox reaction’. Give one example.

Dry raisins were soaked in water for 2 hours, to determine the percentage of water absorbed by raisins. Before final weighing of swollen raisins, the extra water left on the surface of soaked raisins was removed by:

While performing the experiment with raisins to determine the percentage of water absorbed by them, a student made following measurements:

Mass of water in the beaker = 40 g

Mass of raisins before soaking = 5 g

Mass of raisins after soaking for 2 hours = 8 g

Mass of water left in the beaker after the experiment = 35 g

The percentage of water absorbed by raisins is:

The colours of aqueous solutions of CuSO₄ and FeSO₄ as observed in the laboratory are:

(A) pale green and light blue respectively

(B) light blue and dark green respectively

(C) dark blue and dark green respectively

(D) dark blue and pale green respectively

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of a:

1 g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions, the name and the color of the products formed in each case.

Identify the type of reaction taking place in the following case and write the balanced chemical equation for the reaction.
Zinc reacts with silver nitrate to produce zinc nitrate and silver.

Identify the type of reaction taking place in the following case and write the balanced chemical equation for the reaction.
Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

Consider the following chemical equation I and II

1. \[\ce{Mg + 2HCl -> MgCl_2 +H_2}\]
2. \[\ce{NaOH +HCl -> NaCl + H_2O}\]

The correct statement about these equations is:

State whether the given chemical reaction is a redox reaction or not. Justify your answer.

\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]

What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved.

Answer the following question.

What are alloys?

Metal oxides generally react with acids, but few oxides of metal also react with bases. Such metallic oxides are:

1. MgO
2. ZnO
3. Al₂O₃ 
4. Cao

Why covalent compounds are different from ionic compounds?

List three characteristic properties of covalent compounds.

When ethanol reacts with ethanoic acid in the presence of conc. H₂SO₄, a substance with fruity smell is produced. Answer the following:-

(i) State the class of compounds to which the fruity smelling compounds belong. Write the chemical equation for the reaction and write the chemical name of the product formed.

(ii) State the role of conc. H₂SO₄ in the reaction.

Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds.

Name the type of bonds formed in ionic compounds and in the compounds formed by carbon.

Give reason why carbon compounds are generally poor conductors of electricity.

What is meant by a functional group in carbon compounds?