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1.
How many molecules are present in a drop of ethanol, C2H5OH, of mass 2.3 × 10–3 g?
(L = 6.0 × 1023 mol–1)
A.
3.0 × 10 19
B.
3.0 × 1020
C.
6.0 × 1020
D.
6.0 × 1026
(Total 1 mark)
2.
Which sample has the greatest mass?
A.
1 mol of SO2
B.
2 mol of N2O
C.
2 mol of Ar
D.
4 mol of NH3
(Total 1 mark)
3.
What is the total number of hydrogen atoms in 1.0 mol of benzamide, C6H5CONH2?
A.
7
B.
6.0 × 1023
C.
3.0 × 1024
D.
4.2 × 1024
(Total 1 mark)
IB Questionbank Chemistry
1
4.
What is the total number of nitrogen atoms in two mol of NH4NO3?
A.
4
B.
6.02 × 1023
C.
1.20 × 1024
D.
2.41 × 1024
(Total 1 mark)
5.
Which sample has the greatest mass?
A.
6.0 × 1025 molecules of hydrogen
B.
5.0 mol of neon atoms
C.
1.2 × 1024 atoms of silver
D.
1.7 × 102 g of iron
(Total 1 mark)
6.
Which is both an empirical and a molecular formula?
A.
C5H12
B.
C5H10
C.
C4H8
D.
C4H10
(Total 1 mark)
IB Questionbank Chemistry
2
7.
What is the approximate molar mass, in g mol–1, of MgSO4•7H2O?
A.
120
B.
130
C.
138
D.
246
(Total 1 mark)
8.
The relative molecular mass of a gas is 56 and its empirical formula is CH2. What is the
molecular formula of the gas?
A.
CH2
B.
C2H4
C.
C3H6
D.
C4H8
(Total 1 mark)
9.
On analysis, a compound with molar mass 60 g mol–1 was found to contain 12 g of carbon, 2 g
of hydrogen and 16 g of oxygen. What is the molecular formula of the compound?
A.
CH2O
B.
CH4O
C.
C2H4O
D.
C2H4O2
(Total 1 mark)
IB Questionbank Chemistry
3
10.
4.00 mol of a hydrocarbon with an empirical formula of CH2 has a mass of 280 g. What is the
molecular formula of this compound?
A.
C2H4
B.
C3H6
C.
C4H8
D.
C5H10
(Total 1 mark)
11.
Smog is common in cities throughout the world. One component of smog is PAN
(peroxyacylnitrate) which consists of 20.2 % C, 11.4 % N, 65.9 % O and 2.50 % H by mass.
Determine the empirical formula of PAN, showing your working.
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(Total 3 marks)
IB Questionbank Chemistry
4