Question

A student takes about 4 mL of distilled water in four test tubes marked P, Q, R and S. He then dissolves in each test tube an equal amount of one salt in one test tube, namely sodium sulphate in P, potassium sulphate in Q, calcium sulphate in R and magnesium sulphate in S. After that he adds an equal amount of soap solution in each test tube. On shaking each of these test tubes well, he observes a good amount of lather (foam) in the test tubes marked (A) P and Q (B) Q and R (C) P, Q and S (D) P, R and S

Answer 1

Answer:

a} P and Q

Explanation:

water will become hard in the other two cases

Answer 2

Answer:

a. P and Q

Explanation:

as we know that calcium and magnesium salts make the water hard thereby preventing lather formation by soap. so R and S will never form lather..but sodium and potassium don't make water hard so it will form lather after shaking it well