Is iodine a atom, a molecule, an ion or a formule unit?

It's an atom

Explanation:

It can't be a molecule since it's only one element, the ion would've been Iodide (I-), and it's not a formula

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 would be b. 6co2 + 6h2o --> c6h12o6 + 6o2