Chemistry question help

Question

Which pair of compounds will form a buffer?

HNO2 and LiNO2

HCl and NaCl

H2SO3 and MgBr2

Answer 1

HNO₂ and LiNO₂ because for a buffer you need to have a weak acid or a weak base, and the conjugate base or acid, respectively. The only choice that satisfies that is HNO₂ (weak acid) and NO₂^- (conjugate base).