#### Answer

$NH_{3}$ has the highest nitrogen content.

#### Work Step by Step

1-$NH_{3}$
To calculate the percentage composition by mass of nitrogen in a compound, we find the total molar mass of nitrogen in a compound which is 14 and divide by the total molar mass of the compound which is 14+3= 17,
14÷17= 0.823
To find percentage, multiply by 100:
14/17 ×100= 82.35%
2-$CO(NH_{2})_{2}$
First, we calculate the total molar mass of nitrogen in a compound:
2x14=28
Then, we divide it by the total molar mass of the compound: 12+16+(2×14)+(4×1)=60
Therefore,
28/60=0.466
Multiply by 100 to get the percentage by composition:
28/60 x 100= 46.67%
3-$(NH_{3})_{2}SO_{4}$
Total molar mass of nitrogen: 2x14=28
Total molar mass of the compound:(2x14)+(8×1)+32.1+(4×16)= 132.1
Divide the molar mass of nitrogen by the molar mass of the compound:
28÷132.1= 0.2119
Multiply by 100 to find the percentage:
28/132.1 ×100= 21.20%
$NH_{3}$ has the highest nitrogen content.