To determine which equation has both a liquid and a gas as products, let's examine each given chemical reaction step-by-step.
1. First Equation:
[tex]\[
2 \, \text{HgO (s)} \rightarrow 2 \, \text{Hg (l)} + \text{O}_2 \, \text{(g)}
\][/tex]
- Here, we have mercury oxide (HgO) in solid form (s) decomposing into mercury (Hg) in liquid form (l) and oxygen (O₂) in gas form (g).
2. Second Equation:
[tex]\[
2 \, \text{Mg (s)} + \text{O}_2 \, \text{(g)} \rightarrow 2 \, \text{MgO (s)}
\][/tex]
- This reaction involves magnesium (Mg) in solid form (s) reacting with oxygen (O₂) in gas form (g) to produce magnesium oxide (MgO) in solid form (s).
- The products are solid only.
3. Third Equation:
[tex]\[
2 \, \text{KClO}_3 \, \text{(s)} \rightarrow 2 \, \text{KCl (s)} + 3 \, \text{O}_2 \, \text{(g)}
\][/tex]
- Potassium chlorate (KClO₃) in solid form (s) decomposes into potassium chloride (KCl) in solid form (s) and oxygen (O₂) in gas form (g).
- The products are a solid and a gas, but no liquid.
4. Fourth Equation:
[tex]\[
\text{Mg (s)} + 2 \, \text{HCl (aq)} \rightarrow \text{H}_2 \, \text{(g)} + \text{MgCl}_2 \, \text{(aq)}
\][/tex]
- Magnesium (Mg) in solid form (s) reacts with hydrochloric acid (HCl) in aqueous form (aq) to produce hydrogen (H₂) in gas form (g) and magnesium chloride (MgCl₂) in aqueous form (aq).
- The products are a gas and an aqueous solution, but no liquid.
By analyzing each equation, we see that the only equation where both a liquid and a gas are produced as products is the first one:
[tex]\[
2 \, \text{HgO (s)} \rightarrow 2 \, \text{Hg (l)} + \text{O}_2 \, \text{(g)}
\][/tex]
Thus, the correct equation is the first one.
Therefore, the answer is:
1.
