Which of the following will give addition reactions and why?

C₄H₁₀, C₂H₆, C₂H₄, CH₄, C₃H₈, C₃H₄

(a) The process of burning of a hydrocarbon in the presence of air to give CO₂, H₂0, heat and light is known as ............

(b) The sodium salt of a long chain fatty acid is called .........

(c) ............ is better than soap for washing clothes when the water is hard.

(d) The organic acid present in vinegar is.............

CH₄, C₃H₆, C₃H₈, C₄H₆, C₅H₁₂, C₅H₁₀