Question

an element 'X' has a mass number of 19 and contains 10 neutrons . what is the valency of X??​

Answer 1

Answer:

we know that number of protons is atomic number.

and net charge on an atom is given by number of protons minus number of electrons.

Mass number = number of neutrons +number of protons.

Answer 2

The valency of X is 1.

• X has a mass number of 19 and it contains 10 neutrons.
• Thus, the number of protons in X is 19-10=9.
• Thus, the atomic number of X is 9.
• The electronic configuration of X is as follows-
• ${1s}^{2} {2s}^{2} {2p}^{5}$
• Thus it valance shell needs one more electron to complete its octet so, the valency of X is 1.