EVERYDAY SCIENCE

Detailed explanation-1: -Assertion :Pure water obtained from different sources such as river, well, spring, sea etc. always contain hydrogen and oxygen combined in the ratio 1:8 by mass. Reason: A chemical compound always contains elements combined together in same proportion by mass, it was discovered by French chemist, Joseph Proust (1799).

Detailed explanation-2: -In all the water samples, taken from the sea, rivers, lakes or snow-capped mountains, the hydrogen and oxygen ratio is constant, clearly demonstrating the law of definite proportions.

Detailed explanation-3: -An atom is the smallest particle of an element, like oxygen or hydrogen. Atoms join together to form molecules. A water molecule has three atoms: two hydrogen (H) atoms and one oxygen (O) atom. That’s why water is sometimes referred to as H2O.