An isotope of Iodine (atomic number 53) has a mass number of 123 and a half-life of 13 hours. It decays by emitting a beta particle. If the sample has an initial activity of 2000kBq what will be the activity 52 hours later.

so easy. just google the electromagnetic waves and it’ll pop up.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force