$21.$ Which element is fixed in the soil by the use of synthetic ammonia?

$-$ A$)$ Oxygen

$-$ B$)$ Carbon

$-$ C$)$ Nitrogen

$-$ D$)$ Phosphorus

$22.$ Urea provides which essential nutrient to plants?

$-$ A$)$ Potassium

$-$ B$]$ Nitrogen

$-$ C$)$ Phosphorus

$-$ D$)$ Calcium

$23.$ Nitric Acid is essential in the synthesis of:

$-$ A$)$ Potassium Fertilizers

$-$ B$)$ Phosphorus Fertilizers

$-$ C$)$ Nitrogen Fertilizers

$-$ D$)$ Calcium Fertilizers

$24.$ Triple Super Phosphate is an excellent source of:

$-$ A$)$ Nitrogen

$-$ B$)$ Phosphorus

$-$ C$)$ Potassium

$-$ D$)$ Sulfur