Chapter 3 Question 18

Which of the chemical equations below is NOT correctly balanced

A 2Al + 6HCL -> 2AlCl3 + 3H2
B 2Na + 2H2O -> 2NaOH + H2
C Fe3O2 + 2H2 -> 3Fe + 2H2O
D 2Pb(NO3)2 -> 2PbO + 2NO2 + O2

Chapter 3 Question 17

5.4 g of metal M combined with 4.8 g of oxygen to form a compound with the empirical formula M2O3. Determine the relative atomic mass of metal M. (R.A.M: O, 16)

Chapter 3 Question 14

A skin whitening cream contains an oxide of metal M. The metal oxide is reduced in a combustion tube by passing hydrogen gas through it. The result of the experiment is tabulated below.
Mass of empty combustion tube = 35.70 g
Mass of combustion tube + metal oxide (before reduction) = 39.70 g
Mass of combustion tube + metal (after reduction) = 38.10 g
Determine the empirical formula of this metal oxide. (R.A.M: O, 16; M, 48)

Chapter 3 Question 13

Which of the following gases has the same mass? (R.A.M: H, 1; C, 12; N, 14; O, 16; 1 mol of gas occupies 24 dm^3 at room temperature and pressure)

A 4.8 dm^3 NO2 = 6.9 g
B 3.6 dm^3 CO2 = 5.5 g
C 18 dm^3 CH4 = 12 g
D 12 dm^3 NH3 = 3.4 g

Chapter 3 Question 12

If the Avogadro numbe is represented by x, what is the number of carbon dioxide molecules in a gas jar containing 4.8 dm^3 of the gas at room temperature and pressure? (1 mol of gas occupies 24 dm^3 at room temperature and pressure)

A 10x
B 5x
C x/10
D x/5

Chapter 3 Question 11

Matches contain potassium chlorate (V), KClO3. On heating, potassium chlorate (V) decomposes to form potassium chloride and oxygen gas which supports combustion of the matches. Calculate the volume of oxygen gas released at room temperature and pressure when 2.45 g of potassium chlorate (V) is heated. (R.A.M: O, 16; Cl, 35.5; K, 39; 1 mol of gas occupies 24 dm^3 at room temperature and pressure)

Chapter 3 Question 8

Which of the following statements are TRUE for one mole of a substance?

I 1 mol of nitrogen gas contains 6 x 10^23 atoms
II 1 mol of carbon dioxide contains 1.8 x 10^24 atoms
III 1 mol of iron contains 6 x 10^23 molecules
IV 1 mol of water contains the same number of molecules as the number of atoms in 12 g of carbon-12

Chapter 3 Question 7

Calculate the mass of water (H2O) that contains two times more molecules than in 6.4 g methanol (CH3OH). (R.A.M: H, 1; C, 12; O, 16)

Chapter 3 Question 6

Which of the following has the greatest mass? (R.A.M: H, 1; C, 12; N, 14; O, 16; Na, 23; S, 32; K, 39; Pb, 207)

A 0.5 mol NaOH
B 0.4 mol Na2CO3
C 0.3 mol K2SO4
D 0.2 mol Pb(NO3)2

Chapter 3 Question 5

Which of the following gases contain 9 x 10^22 molecules at standard temperature and pressure? (R.A.M: H,1; C, 12; N, 14; O, 16; NA = 6 x 10^23 mole^-1)

I 5.8 g of butane gas, C4H10
II 6.6 g of carbon dioxide gas, CO2
III 2.55 g of ammonia gas, NH3
IV 4.05 g hydrogen cyanide gas, HCN

Chapter 3 Question 4

Calculate the mass of 1.8 x 10^24 methane molecules, CH4. (R.A.M: H, 1,; C, 12; 1 mole contains 6 x 10^23 molecules)

Chapter 3 Question 3

Penicillin is antibiotic. Its molecular formula is C16H18N2OxS. If its relative molecular mass is 350, determine the value of x.

Chapter 3 Question 2

The number of atoms in 1 mole of chlorine gas (Cl2) is equal to the number of atom in...
A 1 mole of magnesium
B 1 mole of carbon dioxide
C 2/3 mole of sulphur dioxide
D 2/3 mole of aluminium oxide

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Chapter 3 Question 1

The relative molecular mass of water is 18. This means a mass of 36 g of water contains...
I 2 molecules of water
II 2 moles of water
III 2 moles ions of water
IV 2 x 6.02 x 10^23 molecules of water

A IV only
B I and IV only
C II and IV only
D II and III only

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