Q. Which of the following is/are the atomic species of Hydrogen?
Choose the correct answer from below given codes:

[A] 1 only

[B] 1 and 2 only

[C] 2 and 3 only

[D] 1, 2 and 3

Answer: D

Explanation: In nature, a number of atoms of some elements have been identified, which have the same atomic number but different mass numbers.

  • For example, take the case of hydrogen atom, it has three atomic species, namely protium (1 1 H), deuterium (2 1 H or D) and tritium (3 1H or T).
  • The atomic number of each one is 1, but the mass number is 1, 2 and 3, respectively.

Source: Science NCERT