Question
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Ethylamine reacts with nitrous acid to form:
A. methyl alcohol
B. ethyl alcohol
C. ethane
D. ethyl nitrite

Answer
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Hint: Ethylamine is a primary amine which belongs to a class of organic compound containing amine functional group. They act as bases when treated with an acid.

Complete step by step answer:
Ethylamine is a one carbon homologue of the simplest primary amine methylamine in the family of amine organic compounds. They contain a \[ - N{H_2}\] group which is basic in nature. It has the ability to accept protons from a proton donor.
Nitrous acid is an acid which only exists in the solution phase. The formula of nitrous acid is\[HN{O_2}\] . It is very effective and used in the preparation of diazonium salts. Actually the reaction of an amine with nitrous acid (\[HO - N = O\] ) is used to identify the presence of primary, secondary or tertiary amines as each of them react in a different way with nitrous acid.
Nitrous acid is unstable intermediate and is prepared instantly before the preparation of diazonium salt. For this a cold and dilute solution of hydrochloric acid (\[HCl\] ) is treated with a solution of sodium nitrite (\[NaN{O_2}\]) at a temperature of \[0 - 5^\circ C\].
\[NaN{O_2} + HCI \to NaCI + HN{O_2}\;\]
The nitrous acid thus produced reacts with ethyl amine and produces ethyl alcohol and nitrogen gas.
$C{H_3}C{H_2}N{H_2}\xrightarrow{{NaN{O_2} + HCl}}\left[ {C{H_3}C{H_2}{N^ + }C{l^ - }} \right]\xrightarrow{{{H_2}O}}C{H_3}C{H_2}OH + {N_2} + HCl$
Thus option B is the correct answer.
Methyl alcohol contains only one carbon atom which is one homologue less than the ethylamine. So it is not formed from ethylamine but is formed from methylamine and nitrous acid.
Ethane is a hydrocarbon with chemical formula \[C2H6\] . It is not formed under the given reaction conditions. Ethyl nitrate is \[C{H_3}C{H_2}N{O_2}\] is not formed in this reaction as it is not a displacement reaction.
And hence optionB is the correct answer.

Note:
 The reaction of aromatic amine with nitrous acid leads to formation of stable diazonium salts. The reaction is named as Sandmayer reaction and is used for the functionalization of benzene rings.