Solute-solvent combination for a solution of camphor in nitrogen gas

The correct answer is option 3. Solid-Gas.

The combination for a solution of camphor in nitrogen gas is 3. Solid-Gas.

Here's why:

Camphor is a solid at room temperature.

Nitrogen gas is a gas at room temperature.

When camphor is exposed to nitrogen gas, it undergoes sublimation, changing directly from a solid to a gas. This gas phase camphor then mixes with the nitrogen gas, forming a homogeneous mixture.

Therefore, in this solution, the solute is the solid camphor and the solvent is the nitrogen gas. This is an example of a gaseous solution, which is less common than liquid solutions but definitely exists.