A gas cylinder contains exactly 15 moles of oxygen gas (O2). How many molecules of oxygen are in the cylinder? 4.01 * 1022 molecules 6.02 * 1023 molecules 9.03 * 1024 molecules 2.89 * 1026 molecules

The answer is 9.03 * 10²⁴ molecules.

Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance.

Make the proportion.

6.02 * 10²³ molecules per 1 mol

x per 15 mol

6.02 * 10²³ molecules : 1 mol = x : 15 mol

x = 6.02 * 10²³ molecules * 15 mol * 1 mol

x = 90.3 * 10²³ molecules

x = 9.03 * 10 * 10²³ molecules

x = 9.03 * 10²³⁺¹ molecules

x = 9.03 * 10²⁴ molecules