Question

Which pair does not show hydrogen isotopes
A. Ortho hydrogen and para hydrogen
B. Protium and deuterium
C. Deuterium and tritium
D. Tritium and protium

Answer 1

Hint: Isotopes are those elements or atoms in which the no of protons are same i.e, their atomic number is the same but the number of neutrons is different so the total of protons and neutrons are different so as their mass number. So, the elements or atoms with the same atomic number but different mass numbers are called isotopes.

Complete Step by Step Answer:
Isotopes can also be called as a family of any element. Not all elements have their isotopes. Different isotopes can show different chemical and physical properties. Hydrogen is the first and the lightest substance in the periodic table. Hydrogen has three isotopes that are found in nature and there are four other isotopes that are synthesised in the laboratory i,e. they are the artificial isotopes of hydrogen.

Now the most important isotopes are the three naturally occurring isotopes which are:
Protium (¹H) – In protium, the number of protons is one and the number of neutrons is zero.
Deuterium [D] (²H) – In deuterium, the number of protons is one and the number of neutrons is one.
Tritium [T] (³H) – In tritium, the number of protons is one and the number of neutrons is two.

So the protium & deuterium, deuterium & tritium, and tritium & protium are isotopes of hydrogen but ortho and para are two different positions for the substituent on the benzene ring.
Thus, Option (A) is correct

Note: Isotopes can be stable or unstable; unstable isotopes are mostly radioactive in nature and all artificial isotopes are radioactive in nature. Only the isotopes of hydrogen have their own unique name which is accepted by the IUPAC nomenclature.