Question

A sample of ammonium phosphate ${(N{H_4})_3}P{O_4}$ contains 3.18 moles of hydrogen atoms. The number of moles of oxygen atom in the sample is
(A) 0.265
(B) 0.795
(C) 1.06
(4) 4.00

Answer 1

Hint In order to find the number of moles of oxygen present in the sample of ${(N{H_4})_3}P{O_4}$ which contains 3.18 moles of hydrogen atom, we can first find the ratio of hydrogen and oxygen. After finding the ratio, we can compare those values with each other.

Complete step by step solution:
Basically, one mole of ammonium phosphate ${(N{H_4})_3}P{O_4}$ has 12 moles of hydrogen.
Therefore, how much moles of ammonium phosphate have 3.18 moles of hydrogen.
$\dfrac{x}{1} = \dfrac{{3.18}}{{12}}$
$x = 0.265$
We found that 0.265 moles of ammonium phosphate molecules have 3.18 moles of hydrogen.
We know that one mole of ammonium phosphate ${(N{H_4})_3}P{O_4}$ has 4 moles of oxygen.
Therefore, 0.265 moles of ammonium phosphate have
$\implies 0.265 \times 4$
$\implies 1.06$moles of oxygen.
Hence, 1.06 moles of oxygen are present in 0.265 moles of ammonium phosphate.

Therefore, the correct answer is option (C) 1.06

Additional Information:
- A mole is the unit of measurement of the amount of substance present.
- One mole of substance or particles is equal to $6.022 \times {10^{23}}$ particles.
- $6.022 \times {10^{23}}$ is the Avogadro number.

Note:
-Another alternate method:
We can also find the number of moles of Oxygen atoms present by counting the individual atoms in ${(N{H_4})_3}P{O_4}$.
N=3
H=12
P=1
O=4
From the above data, we can say that 12 moles of hydrogen correspond to 4 moles of Oxygen.
Let’s say x moles of oxygen corresponds to 3.18 moles of Hydrogen.
Therefore,
$\dfrac{x}{3} = \dfrac{{3.18}}{{12}}$
We can see that Hydrogen and Oxygen are in the 3:1 ratio.
$\dfrac{x}{1} = \dfrac{{3.18}}{3}$
$x = \dfrac{{3.18}}{3}$
$x = 1.06$