50 mL of a 0.100 mol dm^-3 iron (III) nitrate solution is prepared using 15mL of a stock solution. What is the concentration of the stock solution? plz help, just need the answer

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.