Phosphoric Fertilisers

Q. There are some deposits of nitrates and phosphates in earth's crust. Nitrates are more soluble in water. Nitrates are difficult to reduce under the laboratory conditions but microbes do it easily. Ammonia forms large number of complexes with transition metal ions. Hybridisation easily explains the case of sigma donation capability of $N{H}_3$ and $P{H}_3$. Phosphine is a flammable gas and is prepared from white phosphorus.

Among the following, the correct statement is

1. Phosphates have no biological significance in humans
2. Between nitrates and phosphates, phosphates are less abundant in earth's crust
3. Oxidation of nitrates is possible in soil
4. Between nitrates and phosphates, nitrates are less abundant in earth's crust

Q.

Which of the following are fertilizers?

1. Mono-ammonium hydrogen phosphate

2. Superphosphate

3. Triple superphosphate

4. All of the above