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1.
The number of electrons in the K. L. M and N — shells of calcium are respectively
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A.
2,8,8,2
B.
2,2,8,8
C.
2,8, 2, 8,
D.
8,8,2,2
Explanation. Give a better Explanation
K-shells contain maximum of 2-electron, L shells can only contain maximum of 8 electrons, M-shells contain
maximum of 18 electrons, N- contains 32 electrons. Calcium with atomic number 20, shows that electrons are added
to a shell until a stable duplet (for the K-shell) and an octet for L-shells. The increase in the number of electron result
in the electrons occupying the shell with next highest energy level so calcium has 2, 8, 8, 2 (A).


2.
The basic unit of synthetic rubber is
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A.
Isoprene
B.
pentane
C.
butadiene
D.
butene
Explanation. Give a better Explanation
Synthetic rubber is a polymer and the simple unit (monomer) is 2-methylbuta- 1, 3-diene known as isoprene unit (A).


3.
What are the oxidation numbers of manganese in the anions Mn02 and MnO4?
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A.
+7&+6
B.
+2&+2
C.
+4&+4
Explanation. Give a better Explanation
MnO2- = -2
X+(-2x2) =-2
X + -4 = -2
X = +2
MnO4 = -1
X+(-2x4)=-1
X = -1+8
X=+7 (B)


4.
The empirical formula of a hydrocarbon that contains 93.3% carbon is C 12, H = 13
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A.
CH
B.
CH2
C.
C2H
D.
C2H2
Explanation. Give a better Explanation
  C H
% composition Mole ratio 92.3% 7.7%
  92.3/12 7.7/1
Mole ratio of element 7.67 7.7
Smallest mole ratio 7.67 7.67
= 1 1


Empirical formula  =  CH (A)



5.
The type of hybridization in all the carbon in saturated hydrocarbon is
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A.
SP3
B.
SP2
C.
SP
D.
PS2
Explanation. Give a better Explanation
Saturated hydrocarbons have single bond around its carbon, so they exhibit SP3 hybridization (A)


A.
Electron deficient species
B.
Electron rich species
C.
Free radical species
D.
Negatively charged species
Explanation. Give a better Explanation
Electrophiles are electron deficient species like NH4+,H+ (A)


7.
A metallic element X forms an on X2 what will be the formula of tetraoxosulphate of x
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A.
X(SO4)3
B.
XSO4
C.
X2(SO4)
D.
X3SO4
Explanation. Give a better Explanation
The metal must be divalent, i.e. having 2- electrons in its outermost shell to donate to the sulphate, SO42- to give XSO4 (B)


8.
When air is passed through alkaline pyragallol. the component of air absorbed by the pyragallol is
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A.
Oxygen
B.
neon
C.
nitrogen
D.
argon
Explanation. Give a better Explanation
Alkaline pyragallol is used to absorb oxygen (A)


9.
When water drops are added to calcium carbide in a container and the gas produced is passed through jet and lighted, the resultant flame is called an
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A.
Oxyethane flame
B.
Oxyethyleno flame
C.
Hydroxide flame
D.
Oxyacetylene flame
Explanation. Give a better Explanation
CaC2 + 2H2O → C2H2 + Ca(OH)2
Ethyne (ethylene) produced when passed through oxygen give oxyacetylene flame, used for welding (D)


10.
If the relative formula mass of a hydroxide M(OH)3 is 78gmo1-1 what is the relative atomic mass, M?
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A.
61
B.
59
C.
30
D.
27
Explanation. Give a better Explanation
M(OH)3 = 78gmol-1
M+(16+1)3 = 78
M+(17x3) = 78
M=78—51 = 27(D)


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