Which stage in the free radical substitution of methane by chlorine will have the lowest activation
energy?
a ch3• + cl 2 → ch3cl + cl •
b cl • + cl • → cl 2
c cl • + ch4 → ch3• + hcl
d cl 2 → cl • + cl •

I am pretty sure that the stage in the free radical substitution of methane by chlorine which will have the lowest activation energy is B Cl • + Cl • → Cl 2. I choose this option because during termination there is no breaking of bonds within two reactive  radicals which are joined together.

Do hope it will help you!

You didn’t post the image

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer