According to the nuclear reaction $_4Be + _2He^4 \to _6C^{12} + _0n^1$,what is the mass number of the $Be$ atom?

The age of the most ancient geological formations is estimated by:

$A$ photon of hard gamma radiation knocks a proton out of a $_{12}^{24}Mg$ nucleus to form:

Which one of the following notations shows the product incorrectly?

Artificial elements have been prepared by bombardment reactions in high energy accelerators. What is the mass number of the element $X$ produced in the following nuclear reaction: $_{95}^{249}Cf + _{7}^{15}N \rightarrow _{105}X + 4_{0}^{1}n$?

What is $X$ in the following reaction?
${}_{12}Mg^{26} + {}_{1}H^{2} \longrightarrow {}_{12}Mg^{27} + X$