<u>Answer:</u> The chemical equation is written below.
<u>Explanation:</u>
Transmutation is defined as the process in which one chemical isotope gets converted to another chemical isotope. The number of protons or neutrons in the isotope gets changed.
The chemical equation for the reaction of curium-242 nucleus with alpha particle (helium nucleus) follows:

The product formed in the nuclear reaction are californium-245 nucleus and a neutron particle.
It is softer than topaz and and it is softer than diamond (diamond has a Mohs hardness of 10, which is the highest value of the scale)
The answer for this would be 69.6
You can find this on google easily