Question

The number of protons, neutrons and orbital electrons in particles form letters $A$ to $F$ are given in the following table.

Particle	Protons	Neutrons	Electrons
$A$	$3$	$4$	$2$
$B$	$9$	$10$	$10$
$C$	$12$	$12$	$12$
$D$	$17$	$18$	$17$
$E$	$17$	$20$	$17$
$F$	$18$	$22$	$18$

Choose from the table the letters that represent an atom of inert gas.

• A. $B$ and $F$
• B. $F$
• C. $A$ and $B$
• D. $A$

Answer 1

The correct option is B $F$

The outermost orbit of an atom of an inert gas is saturated by the number of electrons given by the formula $2n^2$ where $n=1,2,...$ The atom represent by 'F' has its atomic number $18$ that has electronic configuration $2,8,8$. Which shows that its outermost orbit contains $8$ electrons and hence saturated.