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

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.

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.

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.

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

Define the following:
(i) Mole.
(ii) Molar mass.

112 dm³ of oxygen gas was collected at s.t.p. When a sample of lead nitrate was completely decomposed by heat. Calculate the volume of nitrogen dioxide gas produced.

Three moles of nitrogen gas combined with five moles of hydrogen gas to form ammonium gas by the Haber process
(a) Which reactant is present in smaller amount?
(b) Calculate the grams of the reactant left in the container.
(c) How many moles of are produced?
(d) How many litres of are produced at STP?

 How many chlorine molecules are in 20 cm​ 3​ of chlorine gas at s.t.p.?
 

Calculate the number of ions present in 5 g of copper II nitrate.