(i) Solution B — weak acid
Reason
Weak Acid is an acid which dissociates only partially in aqueous solution thereby producing a low concentration of hydrogen [H+] ions [or H3O+ ions].
For example —
CH3COOH ⇌ CH3COO– + H+ [contains molecules and ions]
(ii) Solution C — strong alkali
Reason
Alkalis react with certain salt solutions to precipitate insoluble hydroxide. Hence,
ZnSO4 + 2NaOH ⟶ Na2SO4 + Zn(OH)2 [gelatinous white precipitate]
(iii) Solution B — weak acid
Reason
Anhydrous acetic acid on cooling forms crystals of glacial acetic acid and acetic acid is a weak acid.
(iv) Ammonium hydroxide (NH4OH)