Question

which equation above represents a precipitation reaction?
\\( 2h_2(g) + o_2(g) \
ightarrow 2h_2o(l) \\)
\\( agno_3(aq) + naoh(aq) \
ightarrow agoh(s) + nano_3(aq) \\)
\\( h_2so_4(aq) + 2naoh(aq) \
ightarrow na_2so_4(aq) + 2h_2o(l) \\)
\\( h_2co_3(aq) \
ightarrow co_2(g) + h_2o(l) \\)

Explanation:

A precipitation reaction forms an insoluble solid (precipitate, marked (s)) from aqueous reactants.

1. Option A is a synthesis/combustion reaction forming liquid water.
2. Option B produces solid $\text{AgOH}$, a precipitate, fitting the definition.
3. Option C is an acid-base neutralization reaction forming water and soluble salt.
4. Option D is a decomposition reaction of a weak acid.

Answer:

B. $\text{AgNO}_3 \ (aq) + \text{NaOH} \ (aq)
ightarrow \text{AgOH} \ (s) + \text{NaNO}_3 \ (aq)$