1. A sample of ammonia weighs 3 grams. what mass of sulphur trioxide contains the same number of molecules as are in 3 grams of ammonia???

2. A spoonful of sugar contains 6 grams. If you dissolve 2 spoonful of sugar for a cup of tea, calculate the no. of sugar molecules in cup.......

Answers of the questions are as follow:

1. Molar mass of ammonia= 17 g

Now 17 g of ammonia contains = 6.022*10²³ molecules

3g of ammonia contains = 6.022*10²³ (3)/17 molecules

Now number of molecules in 3g of ammonia = number of molecules of in x g of sulphur trioxide

Molar mass of SO₃ = 80 g

80 g of SO₃ contains = 6.022*10²³ molecules

In other words, 6.022*10²³ molecules of SO₃ weigh = 80 g

6.022*10²³ (3)/17 molecules of SO₃ weigh = [80/ 6.022*10²³] [6.022*10²³ (3)/17]

 = 14.12g  

2. A spoonful of sugar contains 6 grams. If we dissolve 2 spoonful of sugar for a cup of tea, total amount of sugar will be: 12 grams.

Now molar mass of sugar(C₁₂H₂₂O₁₁) = 342 g

342 g of sugar contains = 6.022*10²³ molecules

12 g of sugar contains = 0.21*10²³ molecules