Question

Potassium nitrate fertilizer contains--of nitrogen.
A. $46$%
B. $44$%
C. $21$%
D. $13$%

Answer 1

Hint:Potassium nitrate is a nitrate fertilizer means it contains nitrogen in the form of nitrate. The percent amount of nitrogen in pure potassium nitrate is almost equal to the atomic mass of nitrogen.

Complete step-by-step answer:Fertilizers are the synthetic or natural substance which is added to the soil so the plants can get nutrition. Fertilizer contains the plant nutrients.
The formula of potassium nitrate is ${\text{KN}}{{\text{O}}_{\text{3}}}$. Potassium nitrate is used as fertilizer used for plant growth. It is water-soluble NK fertilizer.
The plants cannot absorb nitrogen directly from the air, so fertilizers are added which contain nitrogen. This fertilizer supplies nitrogen to the soil which is used by the plants. The nitrogen is present in form of nitrate and the mobility of nitrate is very high, so the nitrate ions are lost by leaching.
The three main micronutrients required for plant growth are Na, P and K. Nitrogen is responsible for leaf growth. Potassium is required for stem growth. Phosphorus is necessary for seed, roots, flower and fruit growth.
So, potassium nitrate fertilizer contains $13$% of nitrogen.

Therefore, option (D) $13$% is correct.

Note:Potassium nitrate is basic so, increase the pH of the soil. The continued use of potassium nitrate fertilizer decreases the acidity of the soil. Potassium nitrate is a binary fertilizer because it provides potassium and nitrogen. The nitrate is absorbed by plants and reduced into nitrite. The nitrite is again reduced to ammonia. The ammonia is used for amino acids and nucleic acids.