The correct option is D Except ethyne, alkynes are odourless.
Physical properties of alkynes:
Physical State:
C2−C4⟶Gases
C5−C12⟶Liquids
≥C13⟶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.