Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

Some Basic Concepts of Chemistry

Long Answer Type

151. Fe₂(SO₄)₃ is the empirical formula of a crystalline compound of iron. It is used in water and sewage treatment for the removal of suspended impurities. Calculate the mass percentage of iron, sulphur and oxygen in the compound.

347 Views

Short Answer Type

152.

What is the empirical formula of the compounds having molecular formula as:
(i) C₆H₆
(ii) C₆H₁₂(iii) H₂O₂
(iv) H₂O
(v) Na₂CO₃(vi) B₂H₆(vii) N₂O₆

155 Views

153. Determine the empirical formula of an oxide of iron which has 69·9% iron and 30.1% dioxygen by mass.

249 Views

Long Answer Type

154.

Silicon (Si = 28) forms a compound with chlorine (Cl = 35·5) in which 5·6g of silicon is combined with 21·3g of chlorine. Calculate the empirical formula of the compound.

651 Views

155.

2.38 g of uranium was heated strongly in a current of air. The resulting oxide weighed 2806 g. Determine the empirical formula of the oxide. (At. mass of U = 238, O = 16).

550 Views

156.

Four grams of copper chloride on analysis was found to contain 1·890 g of copper (Cu) and 2·110 g of chlorine (Cl). What is the empirical formula of copper chloride?

126 Views

157. The atomic mass of metal M is 56. Calculate the empirical formula of its oxide containing 70% of M.

319 Views

158. A chemical compound is found to have the following composition: C = 19·5%, Fe = 15·2%, N = 22·8%, K = 41·5%. Calculate the empirical formula of the compound. What will be the molecular formula if the molecular mass of the compound is 368? Name the compound also.

203 Views

159.
A compound on analysis, is found to have the following composition:
(i) Sodium = 14·31%, (ii) Sulphur = 9·97
(iii) Oxygen = 69·50% (iv) Hydrogen = 6·22%.
Calculate the molecular formula of the compound assuming that whole of hydrogen in the compound is present as water of crystallisation. Molecular weight of the compound is 322.

(i) To calculate the empirical formula of the compound:

(ii) To calculate the molecular formula of the compound.
Empirical formula mass of,

Molecular mass = 322 [given]

Hence,

Whole of the hydtogen is present in the form of water. Thus, 10 water molecules are present in the molecule.
So molecular formula of the compound is Na₂SO₄10H₂O.

98 Views

160.

A sample of hydrazine consists of 87·42% N and 12·58% H by mass. The molecular mass of hydrazine is 32·0 g mol^–1. Calculate its molecular formula.

100 Views