Question

Consider the following reactants. Which produces a gas?


1. NH4Cl(aq) + AgNO3(aq) →
2. Na2CO3(aq) + BaCl2(aq) →
3. Na2S(aq) + HCl(aq) →
4. All of these would produce a gas.

Answer 1

All three of these reactions are double replacement. Therefore, all you need to do is to write the reaction and look up each compound to see what state it is. For example,
NH4Cl(aq) + AgNO3(aq) → NH4NO3(aq) + AgCl(s) etc.