Which of the following contains the same number of atoms? [Ar Ca = 40; S = 32]

• 1 g calcium and 1 g sulphur

• 8 g calcium and 4 g sulphur

• 10 g calcium and 8 gram sulphur

• 8 g calcium and 10 g sulphur

A calcium atom is 3.33 times the mass of a carbon atom. What is the atomic mass of calcium?

• 33

• 40

• 38

• 12

Which of the following pairs of species have the same number of neutrons?

•  $_{29}^{65}Q\ and\ _{16}^{34}Q$  

•  $_{29}^{63}Q\ and\ \ _{29}^{65}Q$  

•  $_{17}^{35}Q\ and\ \ _{29}^{63}Q$  

•  $_{17}^{35}Q\ and\ \ _{16}^{34}Q$  

Which of the following contains the greatest number of molecules?

• 1.0 g of H₂O

• 1.0 g of O₂

• 1.0 g of O₃

• 1.0 g of CO₂

How many moles of H₂O molecules are there in 15.0 g of CuSO₄.5H₂O? [Ar Cu = 63.6; S = 32.1; H =1.0; O = 16.0]

• 0.201

• 0.833

• 0.301

• 0.031

If 0.05 g of potassium hydroxide. KOH is dissolved in 250 mL of water, what is the concentration of solution in g mL^1-?

• 0.4

• 0.3

• 0.1

• 0.2

What is the number of moles of KClO₃ that must decompose to produce 90.0 L of oxygen gas at s.t.p?

• 0.03

• 1.34

• 2.68

• 2.01

A solution contains 28% sulphuric acid by mass. This means that

• 1 litre of solution contains 28 g of sulphuric acid

• 1 litre of solution has a mass of 28 g

• 100 g of solution contains 28 g of sulphuric acid

• 100 g of solution contains 28 % of sulphuric acid

What is the mass maximum mass of ammonia, NH₃ that can be produced by the reaction between 1.7 g of nitrogen gas and 2.5 g of hydrogen gas?[Ar N = 14.0; H = 1.0]

• 0.1 g

• 2.5 g

• 2.1 g

• 1.1 g

What is the volume of 2.0 M HCl that should be mixed with 0.5 L of 0.25 M HCl in order to prepare 1.5 L of 0.50 M HCl?

• 0.31 L

• 2.25 L

• 1.50 L

• 1.00 L