Page $12$

Write the formulas for the following compounds

$80$

lCalculate the energy of a photon having wavelength $250nm.$

Write the electron configuration of the following atoms$/$ions according to aufbau

principle

a$.$ potassium

b$.$ Chloride ion

c$.$ magnesium ion

Complete the following table.

Identify the following elements

a$)$ Contains $3$ electrons in $3$ p subshell.

b$)$ Valence electron configuration is $5s^2$

c$)$ Contains three electrons in the fourth energy leve

d$)$ Has a complete second energy level.

e$)$ Contains two unpaired electrons in its third energy level