2015 - JAMB Chemistry Past Questions and Answers - page 4
31
The leachate of a certain ash is used in local soap because it contain
A
sodium chloride and potassium hydroxide
B
sodium hydroxide
C
potassium hydroxide
D
soluble carbonates and hydrogen carbonate
correct option: b
Sodium hydroxide (NaOH) is made suitable or soap production locally. Option A,C,D will not contribute to soap making
Users' Answers & Comments32
All these are electromagnetic waves except
A
White light
B
Photon
C
X-ray
D
Infrared
correct option: b
Photon is unit of energy that carries light and has zero mass A, C and D are all electromagnetic waves of higher mass
Users' Answers & Comments33
Cu2S(s) + O2(g) = 2CU(s) + SO22(g)
A
+1 to 0
B
0 to +2
C
+2 to +1
D
0 to +1
correct option: a
The oxidation number is from h to O as a result of release of sulphur. Option B, C, D are not the actual oxidation number for copper
Users' Answers & Comments34
The number of isomers formed by C6H14 is
A
4
B
5
C
2
D
3
correct option: b
The number of isomers C6H14 cm is 5. it will not form options A,C, D
Users' Answers & Comments35
There are basic particles from which matter called be made except
A
Salt
B
Atom
C
Ion
D
Molecule
correct option: a
Salt is a chemical used for varieties of purposes, so it’s not part of matter, Atom being the smallest part of molecule and ion are charge which are part of matter
Users' Answers & Comments36
The energy value of petrol can be determined by
A
Bomb calorimeter
B
Catalytic cracker
C
Fractionating column
D
Thermometer
correct option: c
Fractionating column contains petrol with different densities.
Users' Answers & Comments37
What volume of 0.5mldm3 H2SO4 will exactly neutralize 20cm3 of 0.1moldm3 NaOH Solution?
A
2.0cm3
B
5.0cm3
C
6.8cm3
D
8.3cm3
correct option: a
2NaOH + H2SO4 → Na2SO4 + 2H2O
CaVa) ÷ (CbVb) = ratio of acid / ratio of base
0.5Va ÷ (0.1 × 20) = ½
Va = 2.0cm3
Users' Answers & CommentsCaVa) ÷ (CbVb) = ratio of acid / ratio of base
0.5Va ÷ (0.1 × 20) = ½
Va = 2.0cm3
38
A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, Find the molecular formula [H = 1, C = 12, O = 16)
A
CH2O
B
C3H6O3
C
C6H12O6
D
C6H12O3
correct option: c
C = 40%, 40/12 = 3.33
H = 6.7%, 6.7/1 = 6.7
O = 53.3%, 53.3/16 = 3.33
C = 3.33/3.33 = 1
H = 6.7/3.33 = 2
O = 3.33/3.33 = 1
(CH2O)n = 180
(12 + 2 + 16)n = 180
30n = 180
n = 6
= C6H12O6
Users' Answers & CommentsH = 6.7%, 6.7/1 = 6.7
O = 53.3%, 53.3/16 = 3.33
C = 3.33/3.33 = 1
H = 6.7/3.33 = 2
O = 3.33/3.33 = 1
(CH2O)n = 180
(12 + 2 + 16)n = 180
30n = 180
n = 6
= C6H12O6
39
An oxidation state of or in K2CrO7
A
7
B
6
C
5
D
4
correct option: b
The oxidation state of K2Cr2O7 is +6. option A,C,D are the oxidation state of other elements like O7,C14, etc.
Users' Answers & Comments40
The elements that belong to the third period of periodic table are
A
Li, Be, Al and D
B
Na, P, O and Cl
C
B, C, N, and O
D
N2, Mg, S and Ar
correct option: d
Na, Mg, s and Ar one elements that belong to third period of the periodic table. Option A,B,C belong to the other period in the periodic table, second period
Users' Answers & Comments