Question

plz answer these questions​

Answer 1

Answer:

$(100 + 3) \: (100 - 3)$

$= 9991$

Answer 2

Explanation:

(I)

(A) Mass

Mass Number(A) = Proton No.(Z) + Neutron No.(N)

X : A= 16

Y : A= 18

(B) e` Configuration of X

We know : No. of Protons = No. of Neutrons

Hence X has 8 electrons.

Simple e-config : 2, 6

Orbital e-config :

$1 {s}^{2} 2 {s}^{2} 2 {p}^{4}$

(II)

(A) Atomic number

The atom has 7 electrons in its L shell. Hence we can conclude that it has 2 shells i.e K and L. K shell must have 2 electrons as it has to complete it's duplet.

Hence the atom is 2,7 i.e 9 electrons.

Hence Atomic number is 9.

(B) The Element

The element is a halogen namely Flourine (F).

(C) Valence Electrons

The atom tends to be stable like me. Hence he wants to complete his octet. To do this it needs an electron.

Hence Valency is 1.