# Chemistry 2015 | Study Mode

Question 31
A
sodium chloride and potassium hydroxide
B
sodium hydroxide
C
potassium hydroxide
D
soluble carbonates and hydrogen carbonate
##### Explanation
Sodium hydroxide (NaOH) is made suitable or soap production locally. Option A,C,D will not contribute to soap making

Question 32
A
White light
B
Photon
C
X-ray
D
Infrared
##### Explanation
Photon is unit of energy that carries light and has zero mass A, C and D are all electromagnetic waves of higher mass

Question 33
A
+1 to 0
B
0 to +2
C
+2 to +1
D
0 to +1
##### Explanation
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

Question 34
A
4
B
5
C
2
D
3
##### Explanation
The number of isomers C6H14 cm is 5. it will not form options A,C, D

Question 35
A
Salt
B
Atom
C
Ion
D
Molecule
##### Explanation
Salt is a chemical used for varieties of purposes, so its not part of matter, Atom being the smallest part of molecule and ion are charge which are part of matter

Question 36
A
Bomb calorimeter
B
Catalytic cracker
C
Fractionating column
D
Thermometer
##### Explanation

Fractionating column contains petrol with different densities.

Question 37
A
2.0cm3
B
5.0cm3
C
6.8cm3
D
8.3cm3
##### Explanation
2NaOH + H2SO4 Na2SO4 + 2H2O
CaVa) (CbVb) = ratio of acid / ratio of base
0.5Va (0.1 20) =
Va = 2.0cm3

Question 38
A
CH2O
B
C3H6O3
C
C6H12O6
D
C6H12O3
##### Explanation
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

Question 39
A
7
B
6
C
5
D
4
##### Explanation

The oxidation state of K2Cr2O7 is +6. option A,C,D are the oxidation state of other elements like O7,C14, etc.

$$+2 + 2x + (-2\times7) =0$$

$$2x=12$$

$$x = +6$$

Question 40
A
Li, Be, Al and D
B
Na, P, O and Cl
C
B, C, N, and O
D
Na, Mg, S and Ar
##### Explanation

Na, Mg, S and Ar is the set of elements that belong to third period of the periodic table. Option A,B,C have elements which belong to the other period in the periodic table included in them.

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