Question

An atom of an element A written as 9A4 Write its valency​

Answer 1

Answer:

9

down number is valency

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Answer 2

Answer:

9 is the valency because 9 is the mass no. of these.

Explanation: The number of electrons in the outer most shells gives us the valency of the atom. In the same way, the number of protons and neutrons are related to the atomic number and mass number of the atom