Avogadro's Constant says 1 mole of substance has 6.02214086 × 10²³ (Unit is mol⁻¹) particles.
This means, 1 mole = 6.02214086 × 10²³ molecules / atoms
Given methane molecules = 7.31 x 10²⁵
moles of methane = 7.31 x 10²⁵ / 6.02214086 × 10²³ mol⁻¹
= 121.39 mol
Hence, 7.31 x 10²⁵ of methane molecules have 121.39 moles.
