Question

The following reaction shows the production of hydrogen gas from water. This chemical reaction should be classified as _____.

2 H2O 2H2 + O2

synthesis
decomposition
single replacement
double displacement
neutralization

Answer 1

Answer:

The following reaction shows the production of hydrogen gas from water. This chemical reaction should be classified as decomposition ( second choice)

Answer 2

Answer:

B. Decomposition

Explanation:

$2 H_2 O>2H_2+O_2$

Decomposition is the type of reaction in which a compound is broken into smaller  compounds or broken into its elements

$AB>A+B\\\\CaCO_3>CaO+CO_2$

Synthesis is just opposite to decomposition reaction, Elements combine to form a compound

$A+B>AB\\\\CaO+CO_2>CaCO_3$

Single replacement reactions in which replacement takes place at a single place

$A+BC>AB+C\\\\Zn(s)+CuCl_2 (aq)>ZnCl_2 (aq)+Cu(s)$

Double replacement reactions in which replacement occurs two places

$AB+CD>AD+BC\\\\AgNO_3+NaCl>AgCl+NaNO_3$

Neutralization reaction is the reaction between an acid and a base to form salt and water

$HCl+NaOH>NaCl+H_2 O$