English Medium कक्षा १० - CBSE Question Bank Solutions

 Why does menstruation occur?

A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na₂SO₄ in P, K₂SO₄ in Q, CaSO₄ in R and MgSO₄ in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:

(a) P and Q
(b) P and R
(c) P, Q and S
(d) Q, R and S

Distinguish between esterfication and saponification reaction with the help of the chemical equations for each. 

State one use of esterfication process.

State one use of saponification process. 

A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.
(A) Sodium chloride, Potassium chloride
(B) Sodium sulphate, Potassium sulphate
(C) Sodium sulphate, Calcium sulphate
(D) Calcium sulphate, Calcium chloride

While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and 20% aqueous solution of NaOH in a beaker?
(A) The colour of the mixture has become dark brown
(B) A brisk effervescence is taking place in the beaker
(C) The outer surface of the beaker has become hot
(D) The outer surface of the beaker has become cold

Mention the essential material (chemicals) to prepare soap in the laboratory. Describe in brief the test of determining the nature (acidic/alkaline) of the reaction mixture of saponification reaction. 

Explain esterification reaction with the help of a chemical equation. Describe an activity to show esterification.

The sodium salt of a long chain fatty acid is called ______.

______ is better than soap for washing clothes when the water is hard.

What change will you observe if you test soap solution with a litmus paper (red and blue)? Give reason for your observation.

Explain the process of preparation of soap in laboratory.

Why is common salt (sodium chloride) added during the preparation of soap?

What is a detergent?