Question

‘4’g of hydrogen reacts with ‘20’g of oxygen to produce water. The total mass of water formed will be:

• A. 20g
• B. 22.5g
• C. 42.0g
• D. 42.2g

Answer 1

The correct option is B

22.5g

The balanced chemical reaction when hydrogen reacts with oxygen to produce water is.

$\underset{\mathrm{Hydrogen}}{2{\mathrm{H}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

As per balanced reaction, ‘4’g of hydrogen reacts with ‘32’g of oxygen to produce ‘36’g of water.

As per question ‘20’g of oxygen is given.

• ‘32’g of oxygen reacts with ‘4’g of hydrogen to produce ‘36’g of water.
• ‘20’g of oxygen react with ‘$\frac{4\times 20}{32}g$ of hydrogen to produce $\frac{36\times 20}{32}g$ water.
• ‘20’g of oxygen reacts with '2.5'g of hydrogen to produce '22.5'g of water.

Oxygen is the limiting reagent.

When ‘4’g of hydrogen reacts with ‘20’g of oxygen to produce water. The total mass of water formed will be '22.5' g.

Hence, Option (B) is correct.