State the term for the reaction in which the hydrogen of an alkane is replaced by chlorine.

Which of the following statements is wrong about alkanes ?

(A) They are all saturated hydrocarbons.
(B) They can undergo addition as well as substitution reactions.
(C) They are almost non polar in nature.
(D) On complete combustion give out carbon dioxide and water.

Find the odd one out in each case and explain your choice.

(i) C₃H₈ , C₅H₁₀, C₂H₆, CH₄

(ii) Formic acid, Nitric acid, Acetic acid, Propanoic acid.

Identity 'S' : Reddish brown liquid 'S' is dissolved in water. When ethyne is passed through it, turns colourless.