Question

1.2*10^20 molecules of 0xygen

Answer 1

convert into moles by diving the molecule by avagadro number

Answer 2

Answer:

1.2×10²⁰ molecules of O₂ equivalent to 0.2mmol and weigh 6.38mg

Explanation:

Given,

molecules of O₂ = 1.2×10²⁰

moles of O₂ = number of molecules of O₂ / Avogadro's Number

⇒                  =  1.2×10²⁰ / 6.022×10²³ = 1.99×10⁻⁴ moles

⇒                  ≈ 0.2×10⁻³ moles = 0.2mmol.

mass of O₂  = number of moles of O₂ × molar mass of O₂

⇒                 = 0.2×10⁻³ mol. × 32gmol⁻¹ = 6.376×10⁻³g

⇒                 = 6.38mg

Hence, the number of moles is 0.2mmol and the mass is 6.38mg