A sample of `.^(18)F` is used internally as a medical diagnostic tool to look for the effects of the positron decay `(T_(1//2) =110 min)` . How long does it take for `99%` of the `.^(18)F` to decay?

The half-life of iodine-131 is 8.02 days. How long will it take for 80% of the sample to decay?

A threaded rod with 12 turns//cm and diameter 1.18 cm is mounted horizontal. A bar with a threaded hole to match the rod is screwed onto the rod. The bar spins at 216 rev//min . How long will it take for the bar to move 1.50 cm along the rod ?

The radioactive isotope ""^(32)P decays by first order kinetics and has a half-life of 14.3 days. How long does it take for 95.0% of a given sample of 32 p to decay?

The rate constant for the radioactive decay of C-11 is 0.0341 min^(-1) . How long will it take for a sample of C-11 to decrease to (1)/(4) of its original activity?

An insulated container is filled with a mixture of water and ice at t_c = 0^@C . Another container is filled with water that is continuously boiling at t_h = 100^@C . In a series of experiments, the containers are connected by various thick rods that pass through the walls of the containers (see the diagram). The rod is insulated in such a way that there is no heat loss to surroundings. In experiment 1, a copper rod is used, and the ice melts in T_1 = 2 min. In experiment 2, a steel rod of the same cross section is used, and the ice melts in T_2 = 6 min. How long ( in min) would it take to melt the ice if the two rods are used "in series"?

Hydrogen peroxide H_(2)O_(2) (aq) decomposes to H_(2)O (l) and O_(2) (g) in a reaction that is first order in H_(2)O_(2) and has a rate constant k=1.06xx10^(3) min^(-1) (i) How long will it takes for 15% of a sample of H_(2)O_(2) to decompose? (ii) How long will it take for 87.5% of the sample to decompose?