Question

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An atom of element X contains 15 electrons and 16 neutrons.

(a). (I) State the mass number of X.
(ii) Write the electronic
configuration of X.
(b) (I) Write the formula of a chloride of X. pliz , it's urgent. ​

Answer 1

• No of protons=No of electrons=15

Mass no:-No of neutrons+No of protons

`\\ \tt\longmapsto 15+16=31`

Now

• It has atomic no 15 hence its Phosphorus(P)

Electronic configuration:-

`\\ \tt\longmapsto 1s^22s^22p^63s^23p^3`.

• Valency=3

Chloride formula:-

`\\ \tt\longmapsto XCl_3`

or.

`\\ \tt\longmapsto PCl_3`