The ratio by number of atoms for water is H : O =

Question

Question

This question was previously asked in

RRB Pharmacist Exam Paper 2019

Answer 1

Correct Answer: 2 : 1

Rationale:

The chemical formula of water is H₂O, which means each water molecule consists of 2 hydrogen (H) atoms and 1 oxygen (O) atom.
Therefore, the ratio by number of atoms for hydrogen to oxygen in water is 2 : 1.

Explanation of Other Options:

1 : 2

Rationale: This ratio would imply 1 hydrogen atom for every 2 oxygen atoms, which is incorrect for water.

1 : 4

Rationale: This ratio would imply 1 hydrogen atom for every 4 oxygen atoms, which is incorrect for water.

4 : 1

Rationale: This ratio would imply 4 hydrogen atoms for every 1 oxygen atom, which is incorrect for water.

Conclusion:

Given the chemical composition of water (H₂O), the correct ratio by number of atoms of hydrogen to oxygen is 2 : 1.
The other options do not accurately represent the ratio of hydrogen to oxygen atoms in a water molecule.