Chem MC *40marks* with explanation

(1) B
I: Mercury is a metal having a giant metallic structure but it is a liquid at room conditions.
II: The only covalent substance which conducts electricity is graphite. However, it is an element and therefore all covalent compounds cannot conduct electricity.
III: Silver chloride is an ionic substance but it is insoluble in water.
(2) B
Although D is correct. But if we explain from the most basical concept, the fact stated in B can explain for it.
For A, the bonds are of similar strength.
For C, the statement is true but cannot explain the fact since compounds of non-metals do not necessarily have lower m.p. or b.p. than those of metals.
(3) D
Note that in daily life, many electronic devices use silver oxide cell while those with heavier duty need a zinc-carbon cell (or even alkaline manganese cell) to operate.
So to speak, the duty of silver oxide cell is lighter than that of zinc-carbon cell and thus having a smaller charge capacity.

1. D
2. D
3. C