The mole concept and related calculations questions | form three Chemistry

Which description corresponds to a proton?

• Relative mass=1,charge=+1
• Relative mass=,charge=0
• Relative mass=¹/₁₈₄₀, charge=-1
• Relative mass=4,charge=+2

Answer / Solution

A [ Relative mass = 1, charge = +1]

How many moles of oxygen are required for the complete combustion of 2.2 g of C 3 H 8 to form carbon dioxide and water?

1. 0.050 moles
2. 0.15 moles
3. 0.25 moles
4. 0.50 moles 
5. 0.025 moles.

Answer / Solution

UNSOLVED

Which of the following solutions is the most concentrated?
A 50 g of calcium carbonate in 100 cm3 of water
B 60 g of sodium chloride in 200 cm3 of water
C 65 g of potassium nitrate in 100 cm3 of water
D 120 g of potassium sulphate in 200 cm3 of water
E 50 g of sodium hydroxide in 200 cm3 of water.

Answer / Solution

UNSOLVED

20 cm³ of a solution containing 7 g dm^-3 of sodium hydroxide were exactly neutralized by 25 cm³ of 0.10 M hydrochloric acid. Calculate the concentration of sodium hydroxide in moles per dm³.

Answer / Solution

UNSOLVED

A gas at 273°C under a pressure of 1600 mmHg occupies a volume of 190 cm³. What is the volume of gas at STP?

1. 200 cm³
2. 350 cm³
3. 400 cm³
4. 200 dm³

Answer / Solution

UNSOLVED