Question

Assertion: Ammonium hydroxide solution is added to zinc nitrate solution slowly and then in excess we see white precipitate are soluble.
Reason: Ammonium hydroxide solution is added to zinc nitrate solution slowly white precipitate of ammonium nitrate is formed and when ammonium hydroxide is added in excess then the white precipitate is soluble in it.
A.Both assertion and reason are correct and reason is the correct explanation for assertion
B.Both assertion and reason are correct but reason is not the correct explanation for assertion
C.Assertion is correct but reason is incorrect
D.Both assertion and reason are incorrect

Answer 1

Hint: Ammonium hydroxide when added to zinc nitrate solution gives white precipitate. Those precipitates are further soluble and hence, the reaction further leads to the formation of two types of products i.e. a salt and a base.

Complete step by step answer:
Ammonium hydroxide i.e. $N{H_4}OH$ is the chemical formula of a solution of ammonia in water. When ammonia is dissolved in water, the water molecule donates a proton to the $N{H_3}$ molecule. This leads to the formation of an ammonium cation ($N{H_4}^ + $) and a hydroxide ion $(O{H^ - })$ whereas zinc nitrate is a colorless to white crystalline solid. Moreover, it is a non-combustible compound and is highly deliquescent and does dissolve in water and alcohol.
Now, in the given question, both assumption and reason are correct.
When ammonium hydroxide is added to zinc nitrate solution, a white precipitate is formed and this white precipitate dissolves when excess of ammonium hydroxide is added.
Further, zinc nitrate reacts with aqueous ammonia to form a salt and a base. The salt is zinc hydroxide while the base is ammonium nitrate and when they react with each other, white precipitate is formed. The reaction is as shown:
$Zn{(N{O_3})_2} + 2N{H_4}OH \to Zn{(OH)_2} + 2N{H_4}(N{O_3})$
Therefore, both assertion and reason are correct and reason is the correct explanation for assertion.

Hence, option A is correct.

Note:
Ammonium hydroxide solution is an important tool in the manufacturing process of chemical fertilizers. It is used as a solution or as a salt in these fertilizers and moreover it is also used in the production of organic and inorganic chemicals containing nitrogen.