How to do 18,19 and 20 with steps please

Examine the nuclear reacti why is this classified as a nuclear reaction rather than a chemical reaction? it is not balanced. a new compound is formed. a change has occurred in a nucleus. a new element has been formed.

Find the mass by adding the numbers from the three sliders

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is as it changes into other forms of energy.