. 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


Best Answer

Ans. (A) P and Q      

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