Question

Two molecules of hydrogen and one molecule of oxygen reacts to give __ molecule(s) of water.

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (B)

2

Two molecules of hydrogen and one molecule of oxygen reacts to give 2 molecule(s) of water.

Let us see how:

First, let us write the skeletal equation
$H_2+O_2\to H_{2}O$

$\because$ there are 2 oxygen atoms in the reactants side, multiply $H_{2}O$ by 2.

$H_2+O_2\to 2H_{2}O$

$\because$there are 4 hydrogen atoms in the products side, multiply $H_2$ hy 2

Finally, the required reaction is: $2H_2+O_2\to 2H_{2}O$