Question

Last question help im confusion

Answer 1

Remark

The given thing on the right is a positron. The mass for these subatomic particles is considered to be 0. It's atomic number is 1 which means it is a blood relative of a proton.

So essentially what happens is that X is one space to the left on the periodic table. But let's solve this a little bit more formally.

Solution

$_{65}^{147}\text{Tb}\longrightarrow _{z}^{y}\text{x} +_{1}^{0}{e}$

y stays the same at 147. It is z that changes.

65 = z + 1     Subtract 1 from both sides.

64 = z

So the chemical with 64 as its position on the periodic table is

Gadolinium and the answer is C