(1) 18 g (2) 2.99 x 10^-23 g (3) both (1) & (2) are correct (4) 1.66 x 10^-24 g 13. What is the mass of a molecule of CH4: (1) 16 g (2) 26.6 x 10^22 g (3) 2.66 x 10^-23 g (4) 16 NA g 14. Which of the following has the highest mass? (1) 1 g atom of C (2) 1/2 mole of CH4 (3) 10 mL of water (4) 3.011 x 10^23 atoms of oxygen 15. Which of the following contains the least number of molecules? (1) 4.4 g CO