Explanation:
An alpha particles is basically a helium nucleus and it contains 2 protons and 2 neutrons.
Symbol of an alpha particle is
. Whereas a neutron is represented by a symbol
, that is, it has zero protons and only 1 neutron.
Therefore, reaction equation when an aluminum- nuclide transforms into a phosphorus- nuclide by absorbing an alpha particle and emitting a neutron is as follows.

The prefix 'di' means two. Hence two atoms make up a diatomic molecule.
Hope this helps!
Answer: 10.99
Explanation: because you take the Cao 13.9 and take CO2 which is 10.99 and it makes 24.8 . Which is CaCO3.