1) Dissolves in strong acid and alkalis. At O Level, you need to
know that it means it can react with both acid and alkali.
When reacted with acid, it 'acts' like an alkali; and when
reacted with alikali, it 'acts' like an acid. The type we
called it "amphoteric". In your syllabus, you need to know the
basic 3 amphoteric metal (at higher level, there are much more).
The 3 are
Zinc, Aluminium, Lead.
To answer question (1), you need to know your solubility table for
Chlorides. For all level, it is "All chloride soluble in water
except silver, lead, mercury.
The answer to question (1) is Aluminium.
2) option (d) is out, because it can't neutralize nitric acid.
Left with (a), (b), (c).
When sodium hydroxide (a) is added in excess, you will get an
alkali solutions. The neutralization is of the acid-base reaction.
Option (a) is out.
Left with option (b) and (c).
Both calcium carbonate (b) and sodium carbonate (c). Now check
the solubility table for carbonates. You will see "All group I
carbonates are soluble, the rest are insoluble".
If Sodium carbonate is added in excess, it will results in
alkali solution being it is soluble in water (by-product of
neutralization). Option (c) is out.
The answer is Calcium Carbonate (b) because
1) Neutralization. Calcium Carbonate + Nitric Acid -> Calcium
Nitrate + Water + CO2.
Excess Calcium carbonate will remain as solid lumps (won't
dissolve in water). Thus not creating alkali environment.
Answer for question (2) is b.