Question

An element 'X' has mass number 4 and atomic number 2. Write the valency of this element.Will it react with other atoms of different elements?

Answer 1

valency of this atom:

mass number - atomic number = 4 - 2 = 2

This element X is helium.

It will not react with other atoms of different elements because it has completed its duplet state and thus is a stable element or noble gas.

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Answer 2

The given element is helium (He)

• In the periodic table, the element with an atomic number 2 and mass number 4 can be identified as Helium (He).
• Helium belongs to group 18 and is a part of the inert gasses. It is unreactive and doesn't react with different elements atoms as it has a full atomic orbital (2).

Thus, element "x" is helium (He) and it doesn't show reaction with atoms of different elements.