In the equation: X →
226
88
Ra + He
The symbol Xrepresents
A)
222
Th
86
222
B)
Rn
86
230 Th
C)
90
D)
230
90
Rn

²³⁰₉₀Th

Explanation:

X  →  ²²⁶₈₈Ra  +   ⁴₂He

The given equation shows the alpha emission. When He particle emit the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to parent atom the starting atom.  It means the parent atom is  ²³⁰₉₀Th.

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to parent atom the starting atom.

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

₉₂U²³⁸   →   ₉₀Th²³⁴  + ₂He⁴  + energy

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.