NEB Grade 12 Chemistry (Technical Stream) Exam Question Paper 2082 (2025)
National Examination Board (NEB) Class 12 Chemistry (Technical Stream) Exam question. The exam was held in the month of April, 2082 (2025).
Subject : Chemistry (Technical Stream)
Subject Code: 9111
Time: 3 Hrs.
Full Marks: 75
(For regular and partial technical steam students whose first two digits of registration number starts from 79, 80 and 81)
NEB Grade 12 Chemistry MCQs with Answer 2082
1. Which of the following is suitable for titration between ethanoic acid and NaOH
A. Methyl Orange
B. Methyl Red
C. Phenolphthalein
D. Litmus Paper
Answer
Phenolphthalein changes color from colorless in acidic solutions to pink in alkaline solutions, with a pH range of approximately 8.3 to 10.0. When ethanoic acid (a weak acid) reacts with sodium hydroxide (a strong base), the resulting solution has a slightly alkaline pH at the equivalence point, falling within the pH range of phenolphthalein (colorless below pH 8.2 and turns pink to magenta at pH 8.3 to 10.0).
2. Enthalphy change for the reaction N2 + 3H2 ⇌ 2NH3 is -93.7KJ/mol. What kind of reaction is it?
A. Exothermic
B. Indothermic
C. Isothermal
D. Isobaric
Answer
The reaction N2 + 3H2 ⇌ 2NH3 is an exothermic reaction because the enthalpy change (ΔH) is negative (-93.7 kJ/mol).
3. Which of the following species can acts as both Bronsted acidic and Bronsted basic ?
A. HCl
B. H2PO4
C. HCO3-
D. O2
Answer
HCO3- can act as a Bronsted acid by donating a proton (H+) to form CO32-
HCO3- ⇌ H+ + CO32-
It can also act as a Bronsted base by accepting a proton to form H2CO3.
HCO3- + H+ ⇌ H2CO3
4. When copper is heated in air at above 1100° C, which of the following compound is formed ?
A. CuO
B. Cu(OH)2
C. CuCO3
D. Cu2O
Answer
When copper is heated in the presence of oxygen above 1100° C, it reacts to form a black solid copper(II) oxide (CuO).
5. For which manufacturing process, Bassemer converter is used ?
A. Pig Iron
B. Steel
C. Wrought Iron
D. Cast Iron
Answer
The Bessemer process is specifically used to convert pig iron into steel. It involves blowing air through molten pig iron to remove impurities like carbon, manganese, and silicon, thereby producing steel.
6. A substance 'A' reacts with gangue to form fusable mass. The substance 'A' is called.
A. Flux
B. Catalyst
C. Ore
D. Slag
Answer
A flux is added during smelting to react with the impurities (gangue) in the ore, creating a fusible material that can be easily removed.
7. An organic compound boiled with water give phenol. Predict the compound.
A. Chlorobenzene
B. Benzenediazoniumchloride
C. Aniline
D. Benzenesulphonic acid
Answer
When benzene diazonium chloride is boiled with water, the diazonium group is replaced by a hydroxyl group, resulting in the formation of phenol.
8. Which of the following compounds cannot reduce Fehling's solution ?
A. Benzaldehyde
B. Formaldeyde
C. Acetaldehyde
D. Butyraldehyde
Answer
Fehling's solution reacts with aldehydes that have a free alpha-hydrogen. Benzaldehyde, being an aromatic aldehyde, does not have this free alpha-hydrogen due to the presence of the benzene ring attached to the carbonyl group, so it cannot reduce Fehling's solution.
9. Which of the following methods can you apply to convert to rectified spirit into absolute alcohol ?
A. Steam Distillation
B. Vaccume Distillation
C. Simple Distillation
D. Azeotropic Distillation
Answer
To convert rectified spirit (95.6% ethanol) into absolute alcohol (100% ethanol) azeotropic distillation is used.
10. A --O3/Zn/H2O--> Ethanal + Methanal. Identify the compound 'A' ?
A. Ethene
B. Propene
C. But-1-ene
D. But-2-ene
Answer
Ozonolysis of an alkene cleaves the double bond and forms carbonyl compounds (aldehydes or ketones). Propene on ozonolysis gives ethanal and methanal.
11. Which of the following drugs is used to reduce body temperature during high fever ?
A. Analgesic
B. Antiseptic
C. Antipyretic
D. Disinfectant
Answer
The drug used to reduce body temperature during high fever is Antipyretic.