Question

A student prepared 20% sodium hydroxide solution in a beaker containing water. The observations noted by him are given below.
I. Sodium hydroxide is in the form of pellets.
II. It dissolves in water readily.
III. The beaker appears cold when touched from outside.
IV. The red litmus paper turns blue when dipped into the solution.
The correct observation are :

• A. I, II and III
• B. II, III and IV
• C. III, IV and I
• D. I, II and IV

Answer 1

The correct option is D I, II and IV

NaOH present in the form of pellets which react with water readily because it is a base. It is basic and hence, turns red litmus paper blue. The beaker when touched should be hot and not cold as the reaction is exothermic and releases heat.
Only the III statement is incorrect. Option D is correct.