Question

Which of these substances contains the most total atoms per molecule?

Answer 1

C is your answer as it has 9 atoms

Answer 2

Answer: $Ni(NO_3)_2$

Explanation: A molecule is made up by combination of same atoms or different atoms.

1 molecule of $Na_2PFO_3$ consists of 2 atoms of sodium, 1 atom of phosphorous, 1 atom of flourine and three atoms of oxygen. Thus the total number of atoms is 7.

1 molecule of $Na_2PFO_3$ consists of 2 atoms of sodium, 1 atom of phosphorous, 1 atom of flourine and three atoms of oxygen. Thus the total number of atoms is 7.

1 molecule of $H_2SO_4$ consists of 2 atoms of hydrogen, 1 atom of sulfur and 4 atoms of oxygen. Thus the total number of atoms is 7.

1 molecule of $Ni(NO_3)_2$ consists of 1 atom of nickel, 2 atoms of nitrogen and 6 atoms of oxygen. Thus the total number of atoms is 9.

1 molecule of $NbCl_5$ consists of 1 atom of niobium and 5 atoms of chlorine. Thus the total number of atoms is 6.

Thus substance which contains the most total atoms per molecule is $Ni(NO_3)_2$.