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Accept conc H 2SO 4 (reject where concentrated is not mentioned)
Workability √1
Correct method of collection√1
Of the gas √1
The two equations should be mentioned 2 mks
Gas laws

1. X: t 1= 28.3sec RMM = ?
Q 2: t 2= 20.0sec RMM=32
T  MM


T 1 = X
T 2 32

T 1 2 = X
T 2 32

2
28.3 = X 
T 2 32
2
X = 28.3 x 32 
400
X = 64 

2. (a) The rate of diffusion of a gas is inversely proportional to the square root of its density
under the same conditions of temperature and pressure
1
(b) Rate of gas V= / 5 x 100cm
10sec
= 2cm/sec  ½
Rate of W = 10cm
10sec
= 1cm/sec  ½

RV = MW
RW MV = 2 = MW
1 16
2
2 = MW
1 16

4 = MW ; = 4 x 16
1 16 1
MW = 64

3. (a) The volume of a fixed mass of a gas is directly proportional to its absolute temperature at

constant Pressure
(b) Apply combined gas law; P 1V 1= P 2V 2
T 1 T 2
3
-2
3
-2
V 1 = 3.5 x10 m V 2 = 2.8 x 10 m
5
P 1 = 1.0 x 10 Pa P 2= 1.0 x 105Pa  ½
T 1 = 291K T 2= ?
T 2 = P 2V 2T 1
P 1V 1
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