Answer: C.
Explanation:
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of C = 20 g
Mass of H= 1 g
Mass of N= 12 g
Mass of oxygen = 100-(20+1+12)= 67 g
Step 1 : convert given masses into moles.
Moles of C =
Moles of H =
Moles of N =
Moles of O =
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C =
For H =
For N =
For O =
The ratio of C : H : N : O= 2 : 1 : 1 : 5
Hence the empirical formula is