Question

Nitrogen ($N$), Phosphorus ($P$) and Potassium ($K$) are the main nutrients in plant fertilizers. According to an industry convention, the numbers on the label refer to the mass $\%$ of $N$, $P_{2}O$ and $K_{2}O$ in that order. What is $N:P:K$ ratio of a $28:14.2:4.7$ fertilizer in terms of moles of each elements and expressing it as $x:y:1.0$ is :

• A. $1:0.66:1.0$
• B. $20:0.66:1.0$
• C. $8.4:1.3:1.0$
• D. $16.8:1.3:1.0$

Answer 1

Answer: (A)

$1:0.66:1.0$

Given, mass ratio of (Molar mass of $N_2=28$; Molar mass of $P_{2}O=78$; Molar mass of $K_{2}O)=94$) is $28:14.2:4.7=\frac{28}{28}:\frac{14.2}{78}:\frac{4.7}{94}=1:0.18:0.05=20:3.6:1$.