CBSE Class 11-science Answered

Molar mass of N₂O = 44 g

Number of moles of N₂O in 44 g = 1

Number of moles of N₂O in 1g of N₂O = 1 / 44

Number of moles of N₂O in 200 mg or 200 × 10^-3 g of N₂O = 200 × 10^-3 / 44 =  4.545 × 10^-3 moles

Number of moles of N₂O left = 2.89 × 10^-3 moles……(Given)

Total Number of moles of N₂O = 4.545 × 10^-3 moles

Number of moles removed of N₂O = 4.545 × 10^-3 – 2.89 × 10^-3 = 1.655 × 10^-3 moles

1 mole of N₂O = 6.022 × 10²³ molecules of N₂O

1.655 × 10^-3 moles of N₂O = 1.655 × 10^-3 ×  6.022 × 10²³ molecules of N₂O  = 9.96 × 10²⁰ molecules of N₂O