Which statements correctly describe the decay rates of radioactive isotopes? a} it takes two half-lives for a sample to fully decay. b} the exact time when an individual atom will decay can be accurately predicted. c} after each half-life, the amount of radioactive material is reduced by half. d) all radioactive isotopes have the same half-life. e} the decay of individual atoms in a sample of radioactive material is random.

b} The exact time when an individual atom will decay can be accurately predicted.

c} After each half-life, the amount of radioactive material is reduced by half.

Explanation:

All radioactive decay  follows first order kinetics.

Rate law expression for first order kinetics is given by:

where,

k = rate constant

t = time taken for decay process

a = initial amount of the reactant

a - x = amount left after decay process

Expression for calculating half life, which is the time taken by the half of the reactants to decompose is:

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).