Answer:
So sorry if I was wrong but I think it's B. Because from the source states,
https://socratic.org/questions/which-group-on-the-periodic-table-is-the-least-reactive-why
"The least reactive elements are those who have a full outermost valence shell ie they have 8 electrons in the outer shell so elements such as helium, neon, radon or the transition elements."
That would be true, since most other stats include helium, calcium, etc
We know that, M1V1 = M2V2
(Initial) (Final)
where, M1 and M2 are initial and final concentration of soution respectively.
V1 and V2 = initial and final volume of solution respectively
Given: M1 = 12 m, V1 = 35 ml and V2 = 1.2 l = 1200 ml
∴ M2 = M1V1/V2 = (12 × 35)/ 1200 = 0.35 m
Final concentration of solution is 0.35 m
It was a Cambridge UK scientist in the early part of the 20 th century who discovered the electron. His name was J J Thompson.
