Question

In which of the following groups, are the elements written in descending order of their respective atomic weight s ?a) nitrogen, carbon, oxygen, hydrogen b) oxygen, argon, nitrogen, hydrogen c) oxygen, nitrogen, helium, hydrogen d) oxygen, nitrogen, helium, bromine

Answer 1

Option C is the correct answer.

This can be determined by having a closer look at the periodic table and the atomic weights of the elements given in this group which is -

Oxygen - 16u
Nitrogen -14u
Helium - 4u
Hydrogen -1u

In option c, the set of elements given are O, N, He, H. Thus, 'C' is the right answer.

Answer 2

Oxygen, nitrogen, helium, hydrogen are the elements written in descending order of their respective atomic weight.

Option: (c)

Explanation:  

• The atomic weight of oxygen is highest among the given gases this is because its atomic weight is 16 which is constituted by 8 protons and neutrons present in the atom of Oxygen.  

• Following oxygen the weight of nitrogen is 14. This is attributed by the presence of 7 neutrons and 7 protons in the atom of Nitrogen.  

• Following nitrogen is helium. The atomic weight of helium is equal to 4 due to the presence of two neutrons and two protons.

• The weight of hydrogen is the least and it is equal to 1 due to the presence of one proton.

Learn more about atomic weight

Is Atomic Mass and Atomic Weight are same?

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Atomic weight of an element is compared with which of the following to get the atomic weight of that element?

A. Oxygen

B. Carbon

C. Hydrogen

D. Nitrogen​

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