Match List-I with List-II:
List-I (Chemicals)                                   List-II (Use/Preparation/Constituent)
(a) Alcoholic potassium hydroxide                  (i) Electrodes in batteries
(b) Pd/BaSO$$_4$$                                                (ii) Obtained by addition reaction
(c) BHC (Benzene hexachloride)                   (iii) Used for $$\beta$$-elimination reaction
(d) Polyacetylene                                               (iv) Lindlar's catalyst
Choose the most appropriate match:

We need to match each chemical with its use, preparation method, or role.

Alcoholic potassium hydroxide (alcoholic KOH) is a strong base dissolved in ethanol. It is specifically used to carry out $$\beta$$-elimination (dehydrohalogenation) reactions, where an alkyl halide loses HX to form an alkene. So (a) matches with (iii).

$$\text{Pd/BaSO}_4$$ is known as Lindlar's catalyst (often poisoned with quinoline). It is used for the selective partial hydrogenation of alkynes to cis-alkenes. So (b) matches with (iv).

BHC (Benzene hexachloride, $$\text{C}_6\text{H}_6\text{Cl}_6$$) is prepared by the addition of three molecules of $$\text{Cl}_2$$ to benzene in the presence of UV light. Since it is obtained by an addition reaction (not substitution), (c) matches with (ii).

Polyacetylene is a conducting polymer. When doped, it can conduct electricity and is used as electrodes in lightweight batteries. So (d) matches with (i).

Therefore the correct matching is: a-iii, b-iv, c-ii, d-i, which corresponds to Option B.