Question

The discovery of the fact that oxygen and hydrogen combine to form water, was a major step in the development of science. Who made this discovery?
A: Carl Wilhelm Scheele
B: Isaac Newton
C: Joseph Priestley
D: Henry Cavendish

Answer 1

Hint: Hydrogen and oxygen both combine in the definite proportions to form water. Two atoms of hydrogen and one atom of oxygen together form one water molecule. This ratio of hydrogen and oxygen atoms is constant. It does not depend on the way with which it is made.

Complete step by step answer:
Hydrogen and oxygen combine together in the ratio of $2:1$. This means two atoms of hydrogen combine with one atom of oxygen to form one molecule of water. Henry Cavendish discovered the composition of water. He discovered this composition while working on the oxyhydrogen effect. He mixed hydrogen and oxygen together to form an explosion. While doing this experiment he found the composition of water.
This means the correct answer is option D.

Additional information: density of water is $775$ times the density of air. This is why most of the mammals can swim in water. Density of water is maximum at ${4^ \circ }C$. Water is a universal solvent because it can dissolve most of the substances in itself. Law of definite proportions is also called Proust's law or law of constant composition. According to the law of definite proportions atoms combine in a definite proportion to form a particular compound. This ratio doesn’t depend on the source of formation. If this ratio is altered, the compound changes completely.

Note:
Water is the only substance on this planet that can exist as solid, liquid and gas. Temperature and pressure at which these three states co-exist together is called triple point. Triple point of water is at ${0.01^ \circ }C$ and $4.58mm$ of $Hg$.