Reaction With Nitrous Acid

Which of the following on reactions with nitrous acid, followed by treatment with NaOH produces a blue coluration?

Copper metal on treatemet with dilute HNO_(3) produces a gas X,X when passed through acidic solution of stannous chloride, a nitrogen containing compound Y is obtained. Y on reaction with nitrous acid produces a gas Z. Then

Reaction of nitrous acid wiith aliphatic primary aminie in cold gives

Reaction of nitrous acid with aliphatic primary amine in the cold gives

Ethylammc reacts with nitrous acid to form:

Diethylamine reacts with nitrous acid to give