# Question #13431

Jul 15, 2017

A. ${H}_{2} + B {r}_{2} \to 2 H B r$

#### Explanation:

A. ${H}_{2} + B {r}_{2} \to 2 H B r$
This is a synthesis reaction, two reactants form a single product.

B. $M g + {H}_{2} S {O}_{4} \to M g S {O}_{4} + {H}_{2}$
This is clearly an reduction-oxidation reaction; $M g$ is oxidized and the ${H}^{+}$ ions are reduced. This is since the former is more reactive than the latter in the activity series.

C. $N a C l \to N {a}^{+} + C {l}^{-}$
This is merely a dissolution reaction, perhaps in an aqueous solution, such as water.

D. $2 {H}_{2} O + 2 N a \left(s\right) \to 2 N a O H + {H}_{2}$
Another reduction-oxidation reaction, for the same reason as above!