Maharashtra State Board of Technical Education, Mumbai | Chemistry PYQs MCQs | Semester 1 & 2
1. [MSBTE Summer 2019] The atomic number of an element is equal to the number of:
a) Neutrons in the nucleus
b) Electrons in the atom
c) Protons in the nucleus
d) Nucleons in the nucleus
View Answer
c) Protons in the nucleus
Explanation: Atomic number (Z) is defined as the number of protons in the nucleus of an atom, which determines the chemical identity of the element.
2. [MSBTE Winter 2018] The SI unit of amount of substance is:
a) Gram
b) Mole
c) Liter
d) Kilogram
View Answer
b) Mole
Explanation: The mole (mol) is the SI unit for the amount of substance, defined as 6.022 × 10²³ particles (Avogadro’s number).
3. [MSBTE Summer 2022] The pH of a neutral solution at 25°C is:
a) 0
b) 7
c) 14
d) 1
View Answer
b) 7
Explanation: At 25°C, [H⁺] = [OH⁻] = 10⁻⁷ M in pure water, so pH = –log(10⁻⁷) = 7 (neutral).
4. [MSBTE Winter 2020] The gas responsible for greenhouse effect is:
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Argon
View Answer
c) Carbon dioxide
Explanation: CO₂ absorbs infrared radiation and traps heat in the atmosphere, contributing to the greenhouse effect.
5. [MSBTE Summer 2021] The oxidation state of oxygen in H₂O₂ is:
a) +1
b) –1
c) –2
d) 0
View Answer
b) –1
Explanation: In hydrogen peroxide (H₂O₂), each H is +1, so each O must be –1 to balance: 2(+1) + 2(O) = 0 → O = –1.
6. [MSBTE Winter 2019] The number of moles in 18 g of water is:
a) 1
b) 2
c) 0.5
d) 18
View Answer
a) 1
Explanation: Molar mass of H₂O = 18 g/mol. Moles = mass / molar mass = 18 / 18 = 1 mol.
7. [MSBTE Summer 2020] The chemical formula of sodium carbonate is:
a) Na₂CO₃
b) NaHCO₃
c) Na₂SO₄
d) NaCl
View Answer
a) Na₂CO₃
Explanation: Sodium carbonate (washing soda) has the formula Na₂CO₃; NaHCO₃ is sodium bicarbonate.
8. [MSBTE Winter 2021] The catalyst used in the contact process for H₂SO₄ manufacture is:
a) Fe
b) Pt
c) V₂O₅
d) Ni
View Answer
c) V₂O₅
Explanation: Vanadium pentoxide (V₂O₅) is used as a catalyst in the conversion of SO₂ to SO₃ in the contact process.
9. [MSBTE Summer 2018] The hybridization in methane (CH₄) molecule is:
a) sp
b) sp²
c) sp³
d) dsp²
View Answer
c) sp³
Explanation: Carbon in CH₄ has 4 bond pairs and tetrahedral geometry, so hybridization is sp³.
10. [MSBTE Winter 2022] The law of definite proportions was given by:
a) Dalton
b) Proust
c) Avogadro
d) Berzelius
View Answer
b) Proust
Explanation: Joseph Proust stated that a compound always contains the same elements in a fixed proportion by mass.
11. [MSBTE Summer 2019] The gas evolved when zinc reacts with dilute H₂SO₄ is:
a) Oxygen
b) Hydrogen
c) Carbon dioxide
d) Sulfur dioxide
View Answer
b) Hydrogen
Explanation: Zn + H₂SO₄ → ZnSO₄ + H₂↑ (hydrogen gas is evolved).
12. [MSBTE Winter 2018] The functional group in alcohols is:
a) –CHO
b) –COOH
c) –OH
d) –NH₂
View Answer
c) –OH
Explanation: The hydroxyl (–OH) group is the characteristic functional group of alcohols.
13. [MSBTE Summer 2021] The electronic configuration of sodium (Na, Z=11) is:
a) 2, 8, 1
b) 2, 8, 8
c) 2, 8, 2
d) 2, 7, 2
View Answer
a) 2, 8, 1
Explanation: Na: 1s² 2s² 2p⁶ 3s¹ → K=2, L=8, M=1.
14. [MSBTE Winter 2020] The monomer of PVC is:
a) Ethylene
b) Styrene
c) Vinyl chloride
d) Tetrafluoroethylene
View Answer
c) Vinyl chloride
Explanation: Polyvinyl chloride (PVC) is formed by polymerization of vinyl chloride (CH₂=CHCl).
15. [MSBTE Summer 2022] The ore of aluminium is:
a) Haematite
b) Bauxite
c) Magnetite
d) Galena
View Answer
b) Bauxite
Explanation: Bauxite (Al₂O₃·2H₂O) is the primary ore of aluminium.
16. [MSBTE Winter 2019] The chemical name of baking soda is:
a) Sodium chloride
b) Sodium bicarbonate
c) Sodium carbonate
d) Calcium carbonate
View Answer
b) Sodium bicarbonate
Explanation: Baking soda is NaHCO₃, used in cooking and as a mild antacid.
17. [MSBTE Summer 2020] The bond present in N₂ molecule is:
a) Single covalent
b) Double covalent
c) Triple covalent
d) Ionic
View Answer
c) Triple covalent
Explanation: Nitrogen atoms share three pairs of electrons: N≡N (triple covalent bond).
18. [MSBTE Winter 2021] The valency of carbon is:
a) 1
b) 2
c) 3
d) 4
View Answer
d) 4
Explanation: Carbon has 4 valence electrons and forms 4 covalent bonds (tetravalent).
19. [MSBTE Summer 2018] The indicator used in acid-base titration (strong acid vs strong base) is:
a) Litmus
b) Phenolphthalein
c) Methyl orange
d) Both b and c
View Answer
d) Both b and c
Explanation: Both phenolphthalein (8.2–10) and methyl orange (3.1–4.4) can be used; phenolphthalein is more common.
20. [MSBTE Winter 2022] The hardest substance known is:
a) Graphite
b) Diamond
c) Fullerene
d) Graphene
View Answer
b) Diamond
Explanation: Diamond (sp³ hybridized carbon, tetrahedral network) is the hardest natural material.
21. [MSBTE Summer 2019] The chemical formula of bleaching powder is:
a) CaO
b) Ca(OH)₂
c) Ca(OCl)Cl
d) CaCO₃
View Answer
c) Ca(OCl)Cl
Explanation: Bleaching powder is calcium hypochlorite chloride, Ca(OCl)Cl.
22. [MSBTE Winter 2018] The IUPAC name of CH₃COCH₃ is:
a) Propanone
b) Ethanone
c) Propanal
d) Ethanol
View Answer
a) Propanone
Explanation: CH₃COCH₃ has 3 carbon atoms with a keto group; IUPAC name is propanone (acetone).
23. [MSBTE Summer 2021] The metal used in galvanization is:
a) Copper
b) Zinc
c) Aluminium
d) Tin
View Answer
b) Zinc
Explanation: Galvanization is coating iron with zinc to prevent rusting (sacrificial protection).
24. [MSBTE Winter 2020] The atomicity of ozone (O₃) is:
a) 1
b) 2
c) 3
d) 4
View Answer
c) 3
Explanation: Ozone molecule contains 3 oxygen atoms, so atomicity = 3.
25. [MSBTE Summer 2022] The reaction between acid and base to form salt and water is called:
a) Oxidation
b) Reduction
c) Neutralization
d) Saponification
View Answer
c) Neutralization
Explanation: Acid + Base → Salt + Water is a neutralization reaction.
26. [MSBTE Winter 2019] The chemical formula of marble is:
a) CaCO₃
b) CaSO₄·2H₂O
c) CaO
d) SiO₂
View Answer
a) CaCO₃
Explanation: Marble is a metamorphic rock composed mainly of calcium carbonate (CaCO₃).
27. [MSBTE Summer 2020] The gas used in refrigeration is:
a) CO₂
b) NH₃
c) Freon (CCl₂F₂)
d) O₂
View Answer
c) Freon (CCl₂F₂)
Explanation: Freon (dichlorodifluoromethane) was widely used as a refrigerant (now replaced due to ozone depletion).
28. [MSBTE Winter 2021] The number of electrons in the outermost shell of chlorine (Cl) is:
a) 1
b) 3
c) 7
d) 8
View Answer
c) 7
Explanation: Cl (Z=17): 2, 8, 7 → 7 valence electrons.
29. [MSBTE Summer 2018] The process of conversion of gas into liquid is called:
a) Sublimation
b) Condensation
c) Evaporation
d) Fusion
View Answer
b) Condensation
Explanation: Condensation is the change of vapor/gas phase into liquid.
30. [MSBTE Winter 2022] The catalyst used in Haber’s process is:
a) V₂O₅
b) Fe
c) Ni
d) Pt
View Answer
b) Fe
Explanation: Finely divided iron (Fe) with Mo as promoter is used in Haber’s process for ammonia synthesis.
31. [MSBTE Summer 2019] The chemical name of laughing gas is:
a) Nitrogen dioxide
b) Nitrous oxide
c) Nitric oxide
d) Ammonia
View Answer
b) Nitrous oxide
Explanation: N₂O (nitrous oxide) is known as laughing gas due to its euphoric effects.
32. [MSBTE Winter 2018] The molecular mass of H₂SO₄ is:
a) 98 u
b) 64 u
c) 32 u
d) 18 u
View Answer
a) 98 u
Explanation: H₂SO₄ = 2(1) + 32 + 4(16) = 2 + 32 + 64 = 98 u.
33. [MSBTE Summer 2021] The ore of iron is:
a) Bauxite
b) Haematite
c) Calamine
d) Cinnabar
View Answer
b) Haematite
Explanation: Haematite (Fe₂O₃) is the main ore of iron.
34. [MSBTE Winter 2020] The functional group in carboxylic acids is:
a) –OH
b) –CHO
c) –COOH
d) –CO–
View Answer
c) –COOH
Explanation: The carboxyl group (–COOH) is characteristic of carboxylic acids.
35. [MSBTE Summer 2022] The gas used in welding is:
a) Hydrogen
b) Oxygen
c) Acetylene
d) Nitrogen
View Answer
c) Acetylene
Explanation: Oxy-acetylene flame (C₂H₂ + O₂) produces high temperature (~3000°C) for welding.
36. [MSBTE Winter 2019] The chemical formula of plaster of Paris is:
a) CaSO₄·2H₂O
b) CaSO₄·½H₂O
c) CaSO₄
d) CaCO₃
View Answer
b) CaSO₄·½H₂O
Explanation: Plaster of Paris is CaSO₄·½H₂O, formed by heating gypsum (CaSO₄·2H₂O).
37. [MSBTE Summer 2020] The shape of PCl₅ molecule is:
a) Tetrahedral
b) Trigonal bipyramidal
c) Octahedral
d) Linear
View Answer
b) Trigonal bipyramidal
Explanation: PCl₅ has sp³d hybridization and trigonal bipyramidal geometry.
38. [MSBTE Winter 2021] The unit of molarity is:
a) mol/L
b) g/L
c) mol/m³
d) %
View Answer
a) mol/L
Explanation: Molarity (M) = moles of solute / volume of solution in liters → unit: mol/L.
39. [MSBTE Summer 2018] The metal that displaces hydrogen from dilute acids is:
a) Gold
b) Silver
c) Zinc
d) Platinum
View Answer
c) Zinc
Explanation: Metals above hydrogen in reactivity series (like Zn) displace H₂ from dilute acids.
40. [MSBTE Winter 2022] The chemical formula of quicklime is:
a) CaO
b) Ca(OH)₂
c) CaCO₃
d) CaSO₄
View Answer
a) CaO
Explanation: Quicklime is calcium oxide (CaO), obtained by heating limestone.
41. [MSBTE Summer 2019] The hybridization in ethene (C₂H₄) is:
a) sp
b) sp²
c) sp³
d) sp³d
View Answer
b) sp²
Explanation: Each carbon in C₂H₄ has 3 sigma bonds and 1 pi bond → sp² hybridization.
42. [MSBTE Winter 2018] The monomer of natural rubber is:
a) Chloroprene
b) Isoprene
c) Styrene
d) Butadiene
View Answer
b) Isoprene
Explanation: Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene).
43. [MSBTE Summer 2021] The chemical formula of chloroform is:
a) CHCl₃
b) CCl₄
c) CH₂Cl₂
d) CH₃Cl
View Answer
a) CHCl₃
Explanation: Chloroform is trichloromethane, CHCl₃.
44. [MSBTE Winter 2020] The gas responsible for acid rain is:
a) CO
b) SO₂
c) O₃
d) CH₄
View Answer
b) SO₂
Explanation: SO₂ and NOₓ react with water to form H₂SO₄ and HNO₃, causing acid rain.
45. [MSBTE Summer 2022] The number of water molecules in CuSO₄·5H₂O is:
a) 1
b) 3
c) 5
d) 7
View Answer
c) 5
Explanation: Copper sulfate pentahydrate contains 5 molecules of water of crystallization.
46. [MSBTE Winter 2019] The chemical name of vitamin C is:
a) Retinol
b) Ascorbic acid
c) Thiamine
d) Calciferol
View Answer
b) Ascorbic acid
Explanation: Vitamin C is ascorbic acid, essential for preventing scurvy.
47. [MSBTE Summer 2020] The type of reaction in 2H₂ + O₂ → 2H₂O is:
a) Decomposition
b) Combination
c) Displacement
d) Double displacement
View Answer
b) Combination
Explanation: Two reactants combine to form a single product → combination reaction.
48. [MSBTE Winter 2021] The chemical formula of rust is:
a) FeO
b) Fe₂O₃
c) Fe₃O₄
d) Fe₂O₃·xH₂O
View Answer
d) Fe₂O₃·xH₂O
Explanation: Rust is hydrated ferric oxide, Fe₂O₃·xH₂O.
49. [MSBTE Summer 2018] The catalyst used in hydrogenation of oils is:
a) V₂O₅
b) Ni
c) Fe
d) Pt
View Answer
b) Ni
Explanation: Nickel (Ni) is used as a catalyst in the hydrogenation of vegetable oils to form vanaspati ghee.
50. [MSBTE Winter 2022] The number of atoms in one molecule of sulphur (S₈) is:
a) 1
b) 4
c) 8
d) 16
View Answer
c) 8
Explanation: Sulphur exists as S₈ (crown-shaped ring), so one molecule contains 8 atoms.