Question

Which of the following has the lowest density?
(A) Oxygen
(B) Hydrogen
(C) Neon
(D) Carbon

Answer 1

Chemical elements are the purest form of atoms and cannot be broken down into simpler substances by any chemical action. Density is a property that can be defined as the ratio of mass to volume. By comparing the masses of the given elements, the element with the lowest density will be determined.

Complete answer:
The density of a substance or element is defined as the ratio of mass to volume of that substance or element.
Among the given elements, oxygen is an element with atomic number $8$ and has a molar mass of $16amu$ . Hydrogen is an element with atomic number $1$ and has a molar mass of $1amu$ . Neon is an inert gas or noble gas with atomic number $10$ and has a molar mass of $20amu$ . Carbon is an element with atomic number $6$ and has a molar mass of $12amu$ .
Though hydrogen can easily lose one electron in its valence shell, it does not act like a metal. Due to possessing a non-metallic character. Hydrogen is a non-metal and is the lightest element in the periodic table.
Thus, in the given elements, hydrogen is an element with the lowest density.
Option (B) is correct.

Note:
Hydrogen is the element with the lowest density in the periodic table and exists as a gas and osmium is the element with the highest density. Hydrogen is lighter than air, which is a mixture of gases like hydrogen, carbon dioxide, and oxygen.