Gallium has two isotopes, gallium-69 and gallium-71. The average atomic mass of gallium is 69.72. What
are the relative abundances of the two isotopes?

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

it is the most commonly accepted one

the answer is c. nacl