Read also NEB Grade 12 Chemistry Question Paper 2082
NEB Grade 12 Chemistry Solveed Model Paper 2083
1. Identify the equivalent weight of K2Cr2O7 in the following reaction?
K2Cr2O7 + 3H2SO4 + 5(COOH)2 → K2SO4 + Cr2(SO4)3 + 10CO2 + 8H2O
(Cr=52, K=39)
A) 49
B) 294
C) 98
D) 108
View Answer
A) 49
Oxidation state of Cr in K2Cr2O7 is +6 and in Cr2(SO4)3 is +3
Since there are two Cr atoms in K2Cr2O7, the total change in oxidation state (n-factor) is 2 × 3 = 6.
Equivalent Weight = Molar Mass / n-factor
Equivalent Weight = 294 / 6 = 49
2. In a solution that is at equilibrium, what happens to the concentration of H+ ions if the concentration of OH- ions is increased?
a) The concentration of H+ ions increases
b) The concentration of H+ ions decreases
c) The concentration of H+ ions stay the same
d) It depends on the initial concentration of H+ ions
View Answer
B) The concentration of H+ ions decreases
3. Assuming the rate of a reaction is doubled for every 10°C rise in temperature how many times increases the rate of temperature rises from 10°C to 100°C?
a) 112 times
b) 40 times
c) 512 times
d) 256 times
View Answer
C) 512 times
4. For the given reactions:
i. C + O2 → CO2 , ΔH = -x KJmol-1
ii. 2CO + O2 → 2CO2 , ΔH = -y KJmol-1
The enthalpy of formation of CO becomes
View Answer
C)
5. What product would be obtained if red hot copper wire reacts with steam?
a) CuO
b) Cu(OH)2
c) CuH
d) No reaction
View Answer
A) CuO
6. For which manufacturing process, Bessemer converter is used?
a) Ammonia
b) Steel
c) Sodium
d) Glass
View Answer
B) Steel
7. When Sodium phenoxide reacts with methyl bromide it gives
a) Phenol
b) Benzyl alcohol
c) Toluene
d) Anisole
View Answer
D) Anisole
8. Identify the X in the following reaction:
View Answer
B) Sn/HCl
9. Which of the following reagents can be used to distinguish between a phenol and a carboxylic acid?
a) Br2 water
b) Tollen's reagent
c) Fehling's solution
d) NaHCO3
View Answer
D) NaHCO3
10. The colorless sweet smelling liquid compound A which exposed in air forms poisonous phosgene and also react with acetone gives sleep-inducing drug. Predict the product when the compound A reduced in a neutral medium?
a) Methylene chloride
b) Chloroform
c) Carbon tetrachloride
d) Carbon monoxide
View Answer
A) Methylene chloride
11. An oxygen containing organic compound upon oxidation forms a carboxylic acid as the only organic product with its molecular mass higher by 14 units. The organic compound is
a) an aldehyde
b) a primary alcohol
c) a secondary alcohol
d) a ketone
View Answer
B) a primary alcohol