Answer
(a) The molecule contains 7 C atoms, 5 H atoms, 3 N atoms, and 6 O atoms; total: 21 atoms
(b) 0.00102 mol of $CH_{3}(CH_{2})_{4}CH_{2}OH$ contains $1.29 x 10^{22}$ atoms
(c) There are $2.19 x 10^{25}$ F atoms in 12.15 mol $C_{2}HBrClF_{3}$
Work Step by Step
Count the number of atoms per molecule and then use molar mass to calculate the number of atoms in the given weight.