UPSC Prelims 2001 · General Studies

Question 120: Science and Technology

An aqueous solution of copper sulphate is acidic in nature because the salt undergoes

adialysis

belectrolysis

chydrolysis

dphotolysis

AnswerThe answer is (c).

Copper sulphate is the salt of a weak base (copper hydroxide) and a strong acid (sulphuric acid). In water the copper ions react with water, a process called hydrolysis, forming copper hydroxide and leaving free hydrogen ions, so the solution is acidic. Dialysis is a separation method, electrolysis uses electric current, and photolysis uses light.

Why each option is right or wrong

(a) Dialysis is a separation technique using a membrane.
(b) Electrolysis needs an electric current and does not make the solution acidic by itself.
(c) Right: hydrolysis.
(d) Photolysis is decomposition by light.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.