Answer:
D
Explanation:
From periodic table : proton number 19 corresponds to K (potassium)
which is very reactive with water
Isotopes are elements that differ in the number in neutrons while the numner of protons are the same. The answers of the questions are: 1) 18/8 O 2) 22/10 Ne 3) 53/25 Mn 4) 37/24 Cr 5) 106/81 Ti.
Solution :
a). 
This compound is known as sulfur trioxide.
The molecular shape of sulfur trioxide is trigonal planer.
And the bond angle is 120°.
b). 
This compound is known as Nitrous oxide. Here, nitrogen is in the center. There is no lone pair around the nitrogen atom and it forms two sigma bonds with the other two atoms.
It is linear in shape.
The bond angle between them is 180°.
c). 
This compound is known as the Dichloromethane.
The molecular shape of the compound is tetrahedral.
The bond angles is 120°