Very Very Important MCQs for Class 12 Chemistry Board Exam 2080

Very Very Important MCQs for Class 12 Chemistry Board Exam 2080

MCQ - Class 12 Chemistry Board Exam 2080 NEB - Set 1

1. Which of the following is primary standard substance

a. Washing soda

b. oxalic acid dehydrate

c. potassium permanganate

d. ferrous sulphate

2. The pOH of 0.0015 N NaOH is

a. 1.82

b. 8.23

c. 12.18 

d. 10.57

3. Half life period is independent to the initial concentration for the reaction.

a. zero order

b. second order

c. first order 

d. third order

4. AgNO3 can be safely stored in

a. Au vessel 

b. Fe vessel

c. Al vessel 

d. Ni vessel

5. The shapes and properties of complex ions can be

a. Werner's theory 

b. Crystal field theory

c. variable oxidation state 

d. primary valency

6. A white solid halide of mercury forms a white ppt mixture with ammonia.

The halide is

a. HgCl2 

b. HgI2 

c. Hg2I2 

d. Hg2Cl2

7. Alkyl halides react with Dialkyl copper reagents gives alkanes. This

reaction is

a. Corey-House reaction 

b. Wurtz reaction

c. Williamson reaction 

d. Frankland reaction

8. Grignard reagent with HCN followed by hydrolysis gives:

a. alcohol 

b. aldehyde 

c. ketene 

d. carboxylic acid

9. What effect does CaSO4 have on cement?

a. Retard's setting action 

b. Acts as flux

c. Imparts colour 

d. Reduces strength

10. A person is suffering from headache. The physician will suggest him to take

a drug contains

a. Antibiotic 

b. Analgesic 

c. Tranquilizer 

d. Antiseptic

11. Which one the following plants commonly is being used in the production

of paper in Nepal?

a. sallu 

b. allo 

c. harro 

d. sal

Answer with Hint:

b. Oxalic acid dehydrate is a primary standard substance because it is stable and pure, has a high molecular weight, and can be obtained in a highly pure form.

c. The pOH of 0.0015 N NaOH is 1.82, which can be calculated using the formula pOH = -log[OH-].

c. Half-life period is independent of the initial concentration for a first-order reaction.

c. AgNO3 can be safely stored in an Al vessel because aluminum is resistant to corrosion by the nitrate ion present in AgNO3.

a. The shapes and properties of complex ions can be explained by Werner's theory.

a. HgCl2 forms a white ppt mixture with ammonia.

a. Alkyl halides react with Dialkyl copper reagents in the Corey-House reaction to give alkanes.

d. Grignard reagent with HCN followed by hydrolysis gives a carboxylic acid.

a. CaSO4 retards the setting action of cement.

b. A person suffering from a headache will likely be suggested to take an analgesic drug to relieve the pain.

b. Allo is commonly used in the production of paper in Nepal.

MCQ - Class 12 Chemistry Board Exam 2080 NEB - Set 2

1. An aqueous solution of pH 0 is

a. Amphoteric 

b. Acidic

c. Basic 

d. Neutral

2. When rate of reaction is equal to rate constant the order of reaction is

a. Zero order 

b. First order

c. Second order 

d. Third order

3. The value of free energy change at equilibrium is

a. +ve 

b. –ve

c. zero

d. not defined

4. Which of the following is secondary reference electrode

a. Zn/Zn++ 

b. Hydrogen electrode

c. Calomel electrode 

d. Cu/Cu++ electrode

5. Which of the following metal shows +8 oxidation numbers?

a. Au 

b. Pt

c. Hg

d. Os

6. The rare metal present in insulin is

a. Zn 

b. Hg

c. Fe 

d. Cu

7. The most common reaction alkyl halide show is

a. Electrophilic substitution 

b. Nucleophilic substitution

c. Free radical reaction 

d. Electrophilic addition

8. Carbonation of Grignard reagent gives

a. Ketone 

b. Alcohol

c. Alkane 

d. Carboxylic acid

9. Step growth polymer is

a. HCN 

b. Methyl isocyanate

c. H2S 

d. None of this

10. Who discovered the cement?

a. Adult Wurtz 

b. Hofmann

c. Joseph Aspdin 

d. Ostwald

11. Which of the following is not used for making paper?

a. Bamboo 

b. Lokta

c. Jute 

d. Non-fibrous wood

Answer with hint :

b. An aqueous solution of pH 0 is acidic.

a. When the rate of reaction is equal to the rate constant, the order of reaction is zero order.

c. The value of free energy change at equilibrium is zero.

c. Calomel electrode is a secondary reference electrode.

d. Os (osmium) shows +8 oxidation number.

a. Zinc (Zn) is the rare metal present in insulin.

b. Alkyl halides show nucleophilic substitution reaction.

d. Carbonation of Grignard reagent gives carboxylic acid.

d. None of the given options (HCN, methyl isocyanate, and H2S) is a step growth polymer.

c. Joseph Aspdin discovered cement.

d. Non-fibrous wood is not used for making paper.

MCQ - Class 12 Chemistry Board Exam 2080 NEB - Set 3

1. A bivalent metal has equivalent wt. of 12 molecular wt. of its oxide

will be

a.24 

b. 32 

c. 36 

d. 40

2. In a dry cell

a. NH3 gas is not produced

b. NH3 gas is produced and released outside

c. NH3 gas is produced and form a complex salt

d. NH3 gas is produced but gets liquefied

3. Half life is independent of initial concentration in

a. First order

b. second order 

c. third order 

d. zero order

4. Why is precipitate of AgCl is obtained when a drop of AgNO3 is

added in aqueous NaCl solution?

a. Ionic product of AgCl > solubility product

b. Solubility product of AgCl > ionic product of AgCl

c. Solubility product  ionic product of AgCl

d. Solubility product = ionic product of AgCl

5. If an ion absorbs yellow color, it appears

a. Green 

b. Blue 

c. Indigo 

d. Violet

6. The formation of coloured ions in transition metal complex ions can

be well explained by

a. Werner theory 

b. Crystal field splitting

c. Variable oxidation state 

d. primary valency

7. Which pair of metal is unlikely to corrode?

a. Pt and Mg 

b. Cu and Na 

c. Fe and Sn 

d. Ag and Au

8. In Willimson's synthesis, RX reacts with RONa to give ROR, the

better RX is

a. Haloarene 

b. Primary haloalkane

c. Secondary haloalkane 

d. Tertiary haloalkane

9. Which of the following is an organometallic compound?

a. CH3ONa 

b. CH3COONa

c. CH3-Zn-CH3 

d. both a and b

10. Which of the following is an example of chromophore?

a. – C  C - 

b. –NO2

c. methyl isocyanide 

d. N2

11. The presence of chromium oxide in cement makes

a. Green

b. Orange 

c. Blue 

d. Red

Answer with Hint:

Answer: b. 32

Explanation: Equivalent weight of a bivalent metal is equal to its atomic weight divided by its valency. Let the atomic weight and valency of the metal be x and 2 respectively. Therefore, equivalent weight of the metal = x/2. It is given that the equivalent weight is 12. So, x/2 = 12, which gives x = 24. The molecular weight of the oxide of the metal will be equal to the atomic weight of the metal plus the atomic weight of oxygen. So, the molecular weight of the oxide will be 24 + 16 = 32.

Answer: c. NH3 gas is produced and form a complex salt

Explanation: In a dry cell, NH4Cl acts as the electrolyte. When the cell discharges, NH4Cl is broken down into NH3 gas and HCl. The NH3 gas thus produced reacts with the ZnCl2 to form a complex salt, (NH3)2[ZnCl4].

Answer: d. zero order

Explanation: The half-life of a zero-order reaction is independent of the initial concentration. This is because the rate of the reaction is constant and does not depend on the concentration of the reactant.

Answer: a. Ionic product of AgCl > solubility product

Explanation: When a drop of AgNO3 is added to an aqueous solution of NaCl, Ag+ ions react with Cl- ions to form a precipitate of AgCl. The reaction can be represented as follows:

AgNO3 + NaCl → AgCl + NaNO3

The solubility product of AgCl is Ksp = [Ag+][Cl-]. When AgNO3 is added to the solution, the concentration of Ag+ ions increases, leading to the formation of a precipitate if the ionic product [Ag+][Cl-] is greater than the solubility product Ksp.

Answer: b. Blue

Explanation: When an ion absorbs yellow light, it appears blue. This is because the complementary color of yellow is blue. When yellow light is absorbed, the remaining light that is transmitted or reflected appears blue.

Answer: b. Crystal field splitting

Explanation: The formation of colored ions in transition metal complex ions can be explained by the crystal field splitting theory. According to this theory, when a transition metal ion is surrounded by ligands, the d orbitals split into two energy levels, with the three higher energy levels having a higher energy than the two lower ones. When visible light is absorbed by the complex, electrons are excited from the lower energy d orbitals to the higher ones, giving rise to the observed colors.

Answer: a. Pt and Mg

Explanation: Pt and Mg are unlikely to corrode because Pt is a noble metal and Mg has a protective layer of MgO on its surface.

Answer: c. Secondary haloalkane

Explanation: In Williamson's synthesis, an alkyl halide (RX) reacts with an alkoxide ion (RONa) to give an ether (ROR). The reaction proceeds through an S N 2 mechanism, so a secondary alkyl halide is the best RX to use.

Answer: c. CH3-Zn-CH3

Explanation: CH3-Zn-CH3 is an example of an organometallic compound. Organometallic compounds contain at least one bond between a carbon atom and a metal atom.

Answer:  b. –NO2. 

Explanation: A chromophore is a group of atoms in a molecule responsible for its characteristic color. In general, chromophores are groups of atoms that absorb certain wavelengths of light and reflect others, producing the colors that we see.

Answer: a. Green. 

Explanation: The presence of chromium oxide (Cr2O3) in cement can give it a green color. This is due to the absorption of certain wavelengths of light by the chromium ions in the oxide, which reflects a green color to our eyes. The exact shade of green can vary depending on the concentration of chromium oxide in the cement.

MCQ - Class 12 Chemistry Board Exam 2080 NEB - Set 4

1. Aqueous solution of KCN is

a. acidic 

b. basic 

c. neutral 

d. amphoteric

2. The pH of 0.015 N NaOH is

a. 11.82 

b. 12.18 

c. 13.82 

d. 14.18

3. The rate constant for the first order reaction having half life 10 mins

is

a. 1.55 × 10-3 S-1

b. 2.623 × 10-3 S-1

c. 4.732 × 10-3 S-1

d. 6.452 × 10-3 S-1

4. A group of connected fuel cells is

a. fuel battery 

b. fuel cells

c. fuel stack 

d. primary battery

5. Alloy of iron with carbon is heated below its melting point and left if

for cooling slowly. The process is

a. Annealing 

b. Tempering

c. Quenching 

d. Nitriding

6. Primary and secondary valencies of Ni(CO)4 are:

a. 0 and 4 

b. 1 and 4 

c. 4 and 4 

d. 2 and 4

7. A secondary haloalkane having a molecular formula C4H9Cl, on

treatment with alc. KOH followed by ozonolysis yields:

a. propanal and methanal 

b. acetone and formaldehyde

c. methanal 

d. Acetones

8. Which of the following is not sigma-bonded organometallic

compound?

a. Ferrocene 

b. Tetraethyl Lead

c. Dimethyl Lithium 

d. Phenyl Copper

9. The highest present in OPC is:

a. alumina 

b. silica 

c. lime 

d. Iron oxide

10. Which of the following is not contained in material used to make

pulp?

a. cellulose 

b. Lemicelluloses

c. Lignin 

d. Titanium oxide

11. Radioactive substance emits:

a. Alpha particle 

b. X-ray 

c. electrons 

d. Protons

Answer with Hint: 

b. basic. KCN is a salt of a weak acid (hydrocyanic acid) and a strong base (potassium hydroxide), and the resulting solution will be basic.

b. 12.18. The pH of a solution can be calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions. In this case, NaOH is a strong base and will completely dissociate in water to produce OH- ions. Therefore, the [OH-] concentration will be 0.015 M, and the pH can be calculated to be 14 - (-log[0.015]) = 12.18.

c. 4.732 × 10-3 S-1. The rate constant for a first order reaction can be calculated using the equation ln2 / t1/2 = k, where t1/2 is the half-life of the reaction. Plugging in the given values, we get k = ln2 / 10 = 0.0693 min-1. To convert this to units of seconds, we multiply by 60 to get 4.158 × 10-3 s-1, which is closest to option c.

c. fuel stack. A fuel stack is a group of connected fuel cells that work together to produce electricity.

a. Annealing. The process described is annealing, which involves heating a material to a specific temperature and holding it there for a period of time to allow for changes in the material's microstructure. Slow cooling follows the heating process to prevent the material from becoming brittle.

c. 4 and 4. Ni(CO)4 has four CO ligands, which are bonded to the Ni atom via their carbon atoms. The primary valence of Ni in this complex is +2, while the secondary valence is 4, which is equal to the number of CO ligands.

b. acetone and formaldehyde. The reaction described is known as oxidative cleavage, which involves breaking a carbon-carbon double bond by reaction with an oxidizing agent. In this case, the C-C bond in the haloalkane is broken to yield acetone and formaldehyde as the final products.

d. Phenyl Copper. Phenyl copper is a pi-bonded organometallic compound because the bond between the copper atom and the phenyl group is a dative pi-bond.

c. lime. OPC (Ordinary Portland Cement) is a type of cement used in construction. The main component of OPC is calcium silicate, which is produced by heating a mixture of limestone and clay in a kiln. The limestone used in this process is primarily composed of calcium carbonate (CaCO3), which decomposes to form lime (CaO) and carbon dioxide (CO2) during the heating process.

d. Titanium oxide is not contained in material used to make pulp. Pulp is typically made from wood or other plant fibers, and the primary components are cellulose, hemicelluloses, and lignin. Titanium oxide is not a natural component of wood or plant fibers and is not typically added to pulp as a processing aid.

a. Alpha particle. Radioactive substances emit various types of particles or radiation, including alpha particles, beta particles, and gamma rays. Alpha particles are helium nuclei consisting of two protons and two neutrons and have a relatively low penetrating power. They are emitted by certain radioactive elements, such as uranium and radium, during their decay process.

Other MCQS for Practice - Class 12 Chemistry Important MCQs for Board Exam 2080

Which of the following is a strong acid?

a. Acetic acid

b. Hydrochloric acid

c. Citric acid

d. Carbonic acid

Which of the following is a primary alcohol?

a. Methanol

b. Ethanol

c. Propanol

d. Butanol

Which of the following statements about catalysts is true?

a. Catalysts increase the activation energy of a reaction.

b. Catalysts decrease the rate of a reaction.

c. Catalysts are consumed in the reaction.

d. Catalysts provide an alternative pathway for the reaction with a lower activation energy.

Which of the following is a Lewis acid?

a. HCl

b. NaOH

c. FeCl3

d. NH3

What is the oxidation state of sulfur in H2SO4?

a. +2

b. +4

c. +6

d. +8

Which of the following elements is not a noble gas?

a. Helium

b. Neon

c. Argon

d. Radon

Which of the following is a reducing agent?

a. H2O

b. O2

c. NaBH4

d. H2SO4

Which of the following is a conjugate acid?

a. H2O

b. NH3

c. Cl-

d. HCO3-

Which of the following is a primary standard substance for acid-base titrations?

a. NaOH

b. HCl

c. KCl

d. K2Cr2O7

Which of the following is a characteristic property of a metal?

a. High electronegativity

b. High ionization energy

c. Low melting point

d. Low conductivity

Which of the following is a strong base?

a. Ammonia

b. Sodium hydroxide

c. Potassium hydroxide

d. Calcium hydroxide

An aqueous solution of Na2CO3 is:

a. acidic

b. basic

c. neutral

d. amphoteric

The pH of a 0.02 M HCl solution is:

a. 1.30

b. 2.00

c. 2.30

d. 3.00

The rate constant for a second-order reaction having a half-life of 20 seconds is:

a. 0.05 s-1

b. 0.1 s-1

c. 0.2 s-1

d. 0.4 s-1

A device that converts chemical energy into electrical energy is:

a. a fuel cell

b. a battery

c. a capacitor

d. a generator

A process in which a metal is heated and then rapidly cooled is called:

a. annealing

b. tempering

c. quenching

d. nitriding

The primary valency of Fe(CO)5 is:

a. 0

b. 1

c. 5

d. 6

A secondary haloalkane having a molecular formula C6H13Cl, on treatment with alc. KOH followed by ozonolysis yields:

a. butanal and propanal

b. propanone and butanone

c. pentanal and butanone

d. pentanone and propanone

Which of the following is not a transition metal organometallic compound?

a. Ferrocene

b. Titanocene

c. Ruthenocene

d. Phenyl Copper

The main component of glass is:

a. silica

b. alumina

c. lime

d. iron oxide

Which of the following is not a carbohydrate?

a. Glucose

b. Cellulose

c. Starch

d. Cholesterol

Radioactive substance emits:

a. Beta particles

b. Gamma rays

c. Neutrons

d. Photons

Which of the following is a reducing agent?

a. H2SO4

b. HNO3

c. Na2CO3

d. FeSO4

The pH of a 0.01 M solution of NaOH is

a. 11

b. 12

c. 13

d. 14

The half-life of a second-order reaction is directly proportional to

a. the concentration of the reactant

b. the concentration of the product

c. the square of the concentration of the reactant

d. the square of the concentration of the product

When CuSO4 solution is added to NaOH solution, a blue precipitate of

Cu(OH)2 is obtained. This is an example of

a. double decomposition

b. precipitation reaction

c. acid-base reaction

d. redox reaction

Which of the following elements is a good conductor of electricity?

a. Carbon

b. Sulphur

c. Phosphorus

d. Silver

Which of the following is not a characteristic of a Lewis acid?

a. Accepts a pair of electrons

b. Has an empty orbital

c. Donates a pair of electrons

d. Coordinates with a Lewis base

The ability of an atom to attract the shared pair of electrons towards

itself is known as

a. electronegativity

b. electron affinity

c. ionization potential

d. metallic character

Which of the following is a cation?

a. Br-

b. SO4^2-

c. Na+

d. NO3-