Question

Choose the correct statement(s) regarding alkynes :

• A. All alkynes are gases at room temperature.
• B. Alkynes are colourless
• C. Alkynes are highly polar in nature.
• D. Except ethyne, alkynes are odourless.

Answer 1

Answer: (B), (D)

The correct options are
B Alkynes are colourless
D Except ethyne, alkynes are odourless.

Physical properties of alkynes:

Physical State:
$C_2-C_4⟶\text{Gases}$
$C_5-C_{1}2⟶\text{Liquids}$
$\ge C_{13}⟶\text{Solids}$

Colour :
Alkynes are colourless.

Odour :
Alkynes are odourless.An exception is ethyne, which has a characteristic odour
Polarity:
Alkynes are weakly polar in nature.
Solubility:
Generally, polar substances are soluble in polar solvents and non-polar substances are soluble in non-polar solvents.
Generally, polar substances are soluble in polar solvents and non-polar substances are soluble in non-polar solvents.
So, alkynes (weakly-polar) are insoluble in water (polar) and soluble in other non-polar organic solvents.