Know how to solve a half-life problem. If you have 300 grams of a radioactive isotope with a half-life of 15 years: How much of the isotope will you have left after 15 years?
How much of the isotope will you have left after 30 years? How many half-lives will
occur in 45 years?

Adeuteron, 21h, is the nucleus of a hydrogen isotope and consists of one proton and one neutron. the plasma of deuterons in a nuclear fusion reactor must be heated to about 3.02×108 k . what is the rms speed of the deuterons? express your answer using two significant figures.

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.