Question

Predict the products in the following reaction:
AgNO3(aq) + Na2CrO4(aq) →

AgCrO4(s) + Na2NO3(aq)

Ag2CrO4(s) + NaNO3(aq)

Ag(CrO4)2(s) + Na2NO3(aq)

Ag(CrO4)3(s) + Na(NO3)2(aq)

Answer 1

it's simple, check the oxidation states
first separate the reactants as :
\[Ag ^{+1}, NO _{3}^{-1} , Na ^{+1} , CrO _{4}^{-2}\]
now that you know the oxidation states, check the options satisfying the oxidation states
clearly the answer is Ag2CrO4(s) + NaNO3(aq).
generally, there is no way for you to predict the product of a reaction if the hints such as chemical representation, reduction potentials, etc. are not given. if you have MCQ's always use the elimination method, in which you eliminate at least 2 of the wrong or impossible options.
i hope that helped ^_^

Answer 2

Google a solubility rules chart and the products that are insoluble are the products.

Ex. for your first question:
AgNO3(aq) + Na2CrO4(aq) →
This will produce NaNO3 and AgCrO4.
BUT, because All nitrates and all group 1 metals are soluble, NaNO3 will not form
However, AgCrO4 is not soluble.

The products of this reaction are: NaNO3(aq) + AgCrO4(s)