Grand Chemistry MCQs Test for Class 12
1. Which of the following s-block element forms superoxide when burned in air?
Correct: Potassium forms potassium superoxide, KO₂, when burned in excess oxygen; Li and Na form oxide/peroxide under typical conditions.
2. Which of the following formula of nitrides for alkaline earth metal is possible?
Correct: Alkaline earth metals are M²⁺ and nitride is N³⁻, giving the stoichiometric formula M₃N₂.
3. The flame colour of which of the following alkali metal is yellow:
Correct: Sodium gives a bright yellow flame in flame tests due to strong emission near 589 nm (D-lines).
4. The coordination number of cobalt in Na₄[Co(C₂O₄)₃] is
Correct: Oxalate (C₂O₄²⁻) is bidentate; three oxalates coordinate via six donor atoms, giving coordination number 6.
5. An example of a bidentate ligand among the following is:
Correct: Oxalate (C₂O₄²⁻) chelates through two oxygens; OH⁻ and CN⁻ are monodentate, CO₃²⁻ typically binds monodentate.
6. A highly paramagnetic ion among the following is
Correct: High-spin Fe³⁺ (d⁵) has five unpaired electrons, giving the largest paramagnetism among these.
7. 5d series of outer transition elements is
Correct: In common curricular classification, 3d: Sc–Zn, 4d: Y–Cd, 5d: La–Hg group (covering the 5d transition series context).
8. Oxidation of manganese in air gives the following oxide:
Correct: Metallic manganese oxidizes in air to manganoso–manganic oxide, Mn₃O₄, under typical conditions.
9. Which of the following functional group contains a nitrogen atom?
Correct: Amides contain a carbonyl attached to nitrogen (–CONH₂/–CONR₂); alcohols, esters, and ketones lack nitrogen.
10. Fractional distillation of coal give coke, coal tar, coal gas and
Correct: Destructive distillation of coal yields, among others, ammonia liquor along with coke, tar, and coal gas.
11. The number of five membered and six membered rings in C₆₀ Bucky ball are respectively
Correct: Buckminsterfullerene (C₆₀) has 12 pentagons and 20 hexagons forming a truncated icosahedron.
12. Which of the following molecules possess acyl functional group?
Correct: Acyl group is –C(=O)–R; acyl halides (R–CO–Cl) contain the acyl functional group directly.
13. A hydrocarbon with the molecular formula C₇H₁₂ is possibly
Correct: Câ‚™H₂â‚™₋₂ fits alkadienes with two double bonds; C₇H₁₂ corresponds to heptadiene.
14. An organic compound possesses the structural formula CH₃CH=CH–C≡CH, its correct IUPAC name is
Correct: The molecule has both double and triple bonds; numbering gives 3-penten-1-yne.
15. Resorcinol is a phenol, it contains two –OH group at:
Correct: Resorcinol is 1,3-dihydroxybenzene, with hydroxyl groups at positions 1 and 3.
16. Cathode in Castner Kellner cell is:
Correct: In Castner–Kellner cell for NaOH production, mercury acts as cathode forming sodium amalgam.
17. The diagonal member of beryllium is:
Correct: Diagonal relationship in periodic table: Be shows similarities with Al (diagonal member).
18. Purification of sulphur dioxide from arsenic oxide is an essential step in contact process to avoid:
Correct: Arsenic oxide poisons the vanadium pentoxide catalyst; purification prevents catalyst poisoning.
19. Oil of vitriol refers to:
Correct: Oil of vitriol is the old name for concentrated sulphuric acid.
20. An example of a monodentate ligand among the following is:
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