1997 - JAMB Chemistry Past Questions and Answers - page 4
31
The removal of rust from iron by treatment with tetraoxosulphate (IV) acid is based on the?
A
hydrolysis of the iron
B
reaction of acid with base
C
oxidationof the rust
D
dehydration of the iron
correct option: d
Users' Answers & Comments32
Which of the additives could improve the quality of steel?
A
Silicon
B
Sulphur and phosphorus
C
Carbon
D
Chromium and nickel
correct option: d
Users' Answers & Comments33
Sodium hydroxide is prepared commercially from sodium chloride solution by?
A
electrolysis using mercury as cathode
B
hydrolysis in steam using a catalyst
C
electrolysis using iron as anode
D
treating sodium chloride with ammonia and carbon (IV) oxide
correct option: a
Users' Answers & Comments34
A sample of a substance containing only C and H burns in excess O2 to yield 4.4g of CO2
and 2.7 g of H2O. The empirical formula of a substance is?
(C = 12, O = 16, H = 1)
and 2.7 g of H2O. The empirical formula of a substance is?
(C = 12, O = 16, H = 1)
A
CH3
B
CH2
C
CH4
D
C2H24
correct option: a
CxHy + (x + y/4)O2 = XCO2 + (y/2)H2O
4.4 2.7
according to the equation 44x = 9y
Carbon Hydrogen
mole given ratio = (44)/(44), (2.7)/(9) = 0.1,0.3
Empirical formula = (0.1)/(0.1), (0.3)/(o.1) = 1,3 ; CH3
Users' Answers & Comments4.4 2.7
according to the equation 44x = 9y
Carbon Hydrogen
mole given ratio = (44)/(44), (2.7)/(9) = 0.1,0.3
Empirical formula = (0.1)/(0.1), (0.3)/(o.1) = 1,3 ; CH3
35
An undesirable paraffin in the petroleum industry which is particularly prone to knocking is?
A
iso-octane
B
n-heptane
C
iso-heptane
D
n-octane
correct option: b
Users' Answers & Comments36
The reaction of an alkanol with an alkanoic acid in the presence of concentrated H2SO4 will produce an?
A
alkanal
B
alkanoate
C
alkanone
D
alkyne
correct option: b
Users' Answers & Comments37
The final product of the reaction of ethyne with hydrogen iodine is?
A
CH3—CHI2
B
CH2l—CH2I
C
CH3—CI3
D
CH2 = CHI
correct option: a
Users' Answers & Comments38
Synthetic rubber obtained by the polymerization of chlorobutadiene in the presence of sodium is called?
A
teflon
B
isoprene
C
polythene
D
neoprene
correct option: d
Users' Answers & Comments39
The synthetic detergents are preferred to soap for laundry using hard water because?
A
detergents are water soluble while soap is not
B
the calcium salts of detergents are water soluble
C
the magnesium salt of soap is soluble in hard water
D
soap does not have a hydrocarbon terminal chain
correct option: b
Users' Answers & Comments40
25 cm3 of 0.02 M KOH neutralized 0.03 g of a monobasic organic acid having the general formula CnH2n + 1 COOH. The molecular formula of the acid is?
(C = 12, H = 1, O = 16)
(C = 12, H = 1, O = 16)
A
HCOOH
B
C2H5COOH
C
CH3COOH
D
C3H7COOH
correct option: c
Conc. of KOH = 39 x 0.02 = 0.78 g/dm3
25cm3 require 0.03 g of CnH2n + 1 COOH 1000CM3 → x x = (1000) / (25) x 0.03 = 1.2g
CnH2n + 1COOH + KOH → CnH2n + 1 COOK + H2O
from (MAVA) / (MB x VB) = (1) / (1) (MA x 1.2) / (0.02 x 0.78) = (1) / (1)
MA = 0.013
Con. = Molarity x Molecular Mass
Molecular Mass = (0.78) / (0.013) x 60
CnH2n + 1 COOH = 60
12n + 1 (2n + 1) + 12 + 32 + 1 = 6
14n = 60 - 46; n = (14) / (14) = 1
∴ CH3COOH
Users' Answers & Comments25cm3 require 0.03 g of CnH2n + 1 COOH 1000CM3 → x x = (1000) / (25) x 0.03 = 1.2g
CnH2n + 1COOH + KOH → CnH2n + 1 COOK + H2O
from (MAVA) / (MB x VB) = (1) / (1) (MA x 1.2) / (0.02 x 0.78) = (1) / (1)
MA = 0.013
Con. = Molarity x Molecular Mass
Molecular Mass = (0.78) / (0.013) x 60
CnH2n + 1 COOH = 60
12n + 1 (2n + 1) + 12 + 32 + 1 = 6
14n = 60 - 46; n = (14) / (14) = 1
∴ CH3COOH