Chapter 2 Atoms, Molecules, and Ions - Study Questions - Page 95d: 67

$H, P, Ca, O$

Atomic weights: $Ca: 40.078 u,\ P: 30.974 u,\ O: 15.999 u,\ H: 1.008 u$ In the 10,0 g sample: Ca: $3.99\ g \div 40.078 \ g/mol = 0.0996\ mol$ P: $1.85\ g \div 30.974 \ g/mol = 0.0597\ mol$ O: $4.14\ g \div 15.999 \ g/mol = 0.259\ mol$ H: $0.020\ g \div 1.008 \ g/mol = 0.0198\ mol$ So from smallest to largest amount of moles: $H, P, Ca, O$