Question

A solid which bursts into flames on the addition of concentrated Nitric acid is:

• A. Sawdust
• B. Turpentine oil
• C. Alcohol
• D. Ferric sulphate

Answer 1

The correct option is A

Sawdust

The explanation for the correct option

(A): Sawdust

1. Nitric acid is also known as aqua fortis and is a colourless compound when found in its pure state.
2. The chemical formula of Nitric acid is$\mathbf{\left(}{\mathbf{HNO}}_{\mathbf{3}}\mathbf{\right)}$.
3. When a few drops of concentrated Nitric acid fall on sawdust it catches fire.
4. This is happen so because sawdust contains carbon, which gets oxidised to form Carbon dioxide.
5. Therefore, Sawdust will burst into flames with the addition of concentrated Nitric acid. So option A is correct.

The explanation for the incorrect option

(B): Turpentine oil

1. Rectified Turpentine oil reacts with Nitric acid in the presence of alcohol to give Terpinol.

(C): Alcohol

1. Alcohol is a liquid at room temperature.
2. Ethanol forms an explosive when reacted with nitric acid.
3. The reaction is shown below.
   $$\begin{gathered} {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\left(\mathrm{l}\right)+{\mathrm{HNO}}_3\left(\mathrm{l}\right)\to {\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{NO}}_3\left(\mathrm{l}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Ethanol}\mathrm{Nitric}\mathrm{acid}\mathrm{Ethyl}\mathrm{Nitrate} \end{gathered}$$
4. Ethanol reacts with nitric acid to form Ethyl nitrate and water.

(D): Ferric sulphate

1. When Ferric sulphate reacts with Nitric acid it gives paramagnetic substance Nitrosyl Iron (I) Sulphate.

Therefore, option A is correct. Sawdust is a solid which bursts into flames on the addition of concentrated Nitric acid.