The coins in 1991 had more copper in them compared to the coins today. So, that is why it worth 3.3p.
Potential energy stored in a spring => kinetic energy of a toy
Answer:
In general, atomic radius decreases across a period and increases down a group. ... Down a group, the number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital. This results in a larger atomic radius.
A is correct because there is no reaction involved