A 300 grams radioactive sample at initial half life is 3 hours. After 18 hours remaining quantity

In quantitative analysis of second group in laboratory, H₂S gas is passed in acidic medium for precipitation. When Cu²⁺ react with KCN, then for product, true statement is

First product of the reaction between RCHO and NH₂NH₂ is

Reduction by LiAlH₄ of hydrolysed product of an ester gives