How many grams do 1.8 x 1020 atoms of phos- phorus weight​

9.2 x 10⁻³ grams

Explanation:

1mole P = 6.02 x 10²³ atoms

So, no. moles in 1.8 x 10²⁰ atoms P = 1.8 x 10²⁰ / 6.02 x 10²³atoms/mole = 2.99 x 10⁻⁴ mole

Grams P = moles x formula weight of P = 2.99 x 10⁻⁴ mole x 30.9738 g/mole = 9.26 x 10⁻³ grams P

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).