Question

When Al reacts with nitric acid reddish brown fumes were observed. Choose the correct statement(s) regarding the given chemical reaction.​

• A. Nitric acid undergoes oxidation.
• B. Reddish brown fumes indicate evolution of $N{O}_2$ gas.​
• C. $Al{\left(N{O}_3\right)}_3,H_{2}OandN{O}_2$, H2O, and NO2 gas are formed as products.​
• D. Aluminium undergoes reduction.​

Answer 1

Answer: (B), (C)

$Al{\left(N{O}_3\right)}_3,H_{2}OandN{O}_2$, H2O, and NO2 gas are formed as products.​

• When aluminium reacts with aqueous nitric acid it gives aluminium nitrate, nitrogen dioxide gas and water.
• Nitrogen dioxide gas is reddish brown in colour.
• the balanced equation is: $Al\left(s\right)+6HN{O}_3\left(aq\right)\to Al{\left(N{O}_3\right)}_3\left(aq\right)+3H_{2}O\left(l\right)+3N{O}_2\left(g\right)$
• In this reaction, $HN{O}_3$ acts as an oxidising agent and it itself gets reduced.
• Aluminium gets oxidised as it is converted to $A{l}^{+3}$.
• Reddish brown fumes indicate evolution of $N{O}_2$ gas.​ Option A is correct.
• Al undergoes oxidation.Therefore, option B is not correct.
• Nitric acid is an oxidising agent. It undergoes reduction to oxidise the element which reacts with it. So, option C is not correct.
• $Al{\left(N{O}_3\right)}_3,H_{2}OandN{O}_2$ are formed as products.​ Option D is correct.