1. Which of the following composition justifies the secondary alkyl halide?
R₂CHX → Secondary halide has halogen attached to carbon bonded with 2 other carbons.
2. Which of the following alkyl halide cannot produce an alkene while treated with alcoholic potassium hydroxide?
CH₃Br → No β-hydrogen, so elimination (alkene formation) is impossible.
3. C₂H₅MgBr with CO₂ yields:
C₂H₅COOH (Propanoic acid) → Grignard reagent + CO₂ → carboxylic acid with one extra carbon.
4. Grignard’s reagent with ester produces:
Ketone → Ester reacts with 2 moles of Grignard reagent → tertiary alcohol via ketone intermediate. 👉 In practice, the reaction continues to give a tertiary alcohol after hydrolysis, but in MCQs the expected answer is Ketone.
5. Amine act as bases because:
They accept H⁺ → 👉 Lone pair on nitrogen makes amines Lewis bases.
6. The structure of primary amine is:
Tetrahedral pyramidal 👉 Due to sp³ hybridization and lone pair on nitrogen.
7. Alkyl amine when reacts with nitrous acid (HNO₂) in the presence of HCl yields:
Alcohol 👉 Primary aliphatic amine + nitrous acid → alcohol via diazotization.
8. Sɴ₂ reaction occurs most easily if the substrate molecule is:
CH₃I 👉 Least steric hindrance → fastest Sɴ₂ reaction.
9. Suitable reagent required for the synthesis of propane (C₃H₈) from CH₃MgI is:
C₂H₅Cl 👉 Reaction with CH₃MgI gives propane(alkylation).
10. The rate of Sɴ₁ mechanism depends upon:
Conc. of substrate only 👉 Sɴ₁ is unimolecular, rate depends only on substrate concentration.
11. The atomic number of an element belonging to group VIA and 3rd period is:
👉 Group 16 → ns² np⁴ valence.👉 Period 3 → n=3 shell, so 3s² 3p⁴.👉 Total electrons = 16 → atomic number 16.
12. Sodium amalgam is an alloy of:
🔎 Amalgam means an alloy of a metal with mercury (Hg).Classic examples: dental amalgam (silver + mercury), sodium amalgam (sodium + mercury). 👉 Sodium amalgam is specifically an alloy of sodium (Na) and mercury (Hg). Prepared by dissolving sodium metal in mercury. Used as a reducing agent in organic and inorganic chemistry (e.g., in Birch reduction, or in preparing hydrogen gas from water).
13. Elements of group IB are called
🔎 Group IB (old notation) corresponds to Group 11 in modern IUPAC numbering. Elements in this group are: Copper (Cu), Silver (Ag), Gold (Au). 👉 These metals have historically been used to make coins because of their durability, malleability, and resistance to corrosion. Hence, they are called Coinage metals.
14. Which lists species with the same electron configuration?
🔎 S (Z=16): neutral config = [Ne]3s² 3p⁴ → S²⁻ = [Ne]3s² 3p⁶ = 18 e⁻ (same as Ar).
🔎 Cl (Z=17): neutral = [Ne]3s² 3p⁵ → Cl⁻ = [Ne]3s² 3p⁶ = 18 e⁻ (same as Ar).
🔎 K (Z=19): neutral = [Ar]4s¹ → K⁺ = [Ar] = 18 e⁻.
👉 All three (S²⁻, Cl⁻, K⁺) have 18 electrons → same configuration (isoelectronic with Ar).
15. The metal forms superoxide is
🔎 A superoxide contains the ion O₂²⁻. Metals that form superoxides are typically large alkali metals because they can stabilize this big anion. Potassium (K), Rubidium (Rb), and Cesium (Cs) all form superoxides (KO₂, RbO₂, CsO₂). These are used, for example, in oxygen supply systems because they release O₂ when reacting with CO₂ or moisture. 👉 Smaller alkali metals (like Li, Na) form normal oxides or peroxides instead, not superoxides.
16. The Outer Electronic Configuration of an element is 4s² 3d¹⁰ 4p¹, its group and period are respectively
🔎 Outer configuration shows ns² np¹ → III-A (Group 13). 🔎 Highest n = 4 → Period 4. 👉 Therefore, the element is Gallium (Ga) with atomic number 31.
17. EDTA is the ______________ type of Ligand.
🔎 EDTA = Ethylenediaminetetraacetic acid. It is a common chelating agent used in coordination chemistry and medicine. 🔎 EDTA has six donor sites; 2 nitrogen atoms (from –NH₂ groups) and 4 oxygen atoms (from carboxylate –COO⁻ groups). 👉 A ligand that can attach through six donor atoms is called hexadentate (hexa-dentate). EDTA coordinates through six donor atoms (2N + 4O) → it is a hexa-dentate ligand. 👉 EDTA can wrap around a metal ion and form very stable complexes because of this property.
18. Energy of t₂g orbital is ………. than that of eg orbital.
🔎 In an octahedral crystal field, ligands approach along the axes.eg orbitals (dₓ²₋y², dz²) lie directly along the axes → maximum repulsion → higher energy. 🔎 t₂g orbitals (dxy, dxz, dyz) lie between the axes → less repulsion → lower energy. 👉 Therefore, t₂g orbitals have lower energy than e g orbitals.
19. The metal ion having highest number of unpaired electrons is:
🔎 Mn (Z = 25): [Ar] 3d⁵ 4s²; remove 2 from 4s → Mn²⁺: [Ar] 3d⁵ → 5 unpaired electrons (all 5 orbitals singly occupied obeying Hund’s rule).
🔎 Fe (Z = 26): [Ar] 3d⁶ 4s²; remove 2 from 4s → Fe²⁺: [Ar] 3d⁶ → 4 unpaired electrons.
🔎 Co (Z = 27): [Ar] 3d⁷ 4s²; remove 2 from 4s → Co²⁺: [Ar] 3d⁷ → 3 unpaired electrons.
🔎 Ni (Z = 28): [Ar] 3d⁸ 4s²; remove 2 from 4s → Ni²⁺: [Ar] 3d⁸ → 2 unpaired electrons.
👉 Mn²⁺ has a half‑filled 3d⁵ configuration, which gives the maximum stability and the highest number of unpaired electrons (5) among the given ions.
20. On burning in excess of Oxygen Sodium forms its:
🔎 Sodium forms peroxide (Na₂O₂) when burned in excess oxygen. Lithium forms normal oxide (Li₂O). 👉 Potassium, Rubidium, Cesium form superoxides (KO₂, RbO₂, CsO₂) because their larger cations stabilize the O₂²⁻ ion.
21. The process of covering iron sheets by a layer of Zinc is known as:
👉 Galvanizing protects iron sheets from corrosion by forming a zinc layer, which acts as a sacrificial coating — zinc oxidizes first, saving the iron underneath.
22. The chemical name of laughing gas is
👉 Laughing gas is N₂O, not NO (nitric oxide), not N₂O₅ (nitrogen pentaoxide), and not N₂O₃ (nitrogen trioxide). Therefore, option (b) is correct.👉 Commonly used in dentistry and minor surgery as an anesthetic. Known for causing mild euphoria → hence the name “laughing gas.” Laughing gas = Nitrous oxide with Formula N₂O. It is a colorless gas with a slightly sweet odor.
23. Which one of the following is the formula of superoxides of alkali metals (M)?
👉 Superoxide ion = O₂²⁻. 👉 Alkali metal cation = M⁺. 👉 General Formula of superoxides of alkali metals (M)= MO₂
24. The oxide of beryllium is:
👉 BeO is amphoteric because of its small cation size and partial covalent character.
👉 It can dissolve in both acidic and basic solutions, unlike heavier alkaline earth oxides which are strongly basic.
👉 Amphoteric metals like Be, Al, Zn, Cr, Mn, Pb, Sn etc. form amphoteric oxides especially in the intermediate oxidation state having dual character of reacting both acids and bases.
👉 Amphoteric metals (Be, Al, Zn, Cr, Mn, Pb, Sn, etc.) are typically in the borderline region of the periodic table — not strongly metallic like alkali/alkaline earth metals, and not strongly non metallic either.
👉 Their oxides therefore show dual character:
⚡ React with acids → behave like bases (forming salts such as AlCl₃, ZnCl₂).
⚡ React with bases → behave like acids (forming aluminates, zincates, stannates, etc.).
25. Which of the following form normal oxide?
👉 Only Lithium of alkali metals among the given options forms a normal oxide (Li₂O). Others form peroxide (Na₂O₂), superoxide (KO₂), or normal basic oxide (CaO).
26. The elements of which one of the following pairs of group would be expected to form compound of formula MX:
👉 Target formula MX implies charges balance 1:1: M²⁺ with X²⁻ or M¹⁺ with X¹⁻.👉 Group IIA (alkaline earth metals, M²⁺) with Group VIA (chalcogens, X²⁻) form oxides/sulfides of type MX (e.g., MgO, CaO, SrS).
27. The electron configuration of atoms of element X is [Ar] 3d¹⁰ 4s². Which is the most likely formula for the compound of this element and oxygen?
🔎 Electron configuration: [Ar] 3d¹⁰ 4s² corresponds to Zinc (Zn, atomic number 30). 🔎 Zinc almost always shows +2 oxidation state (stable due to filled 3d¹⁰ subshell). So in compounds, Zn → Zn²⁺. 🔎 Oxygen typically forms O²⁻. 👉 To balance charges: Zn²⁺ + O²⁻ → ZnO (XO).
28. Which one of the following represents the pair of metalloids?
👉 The true pair of metalloids among the given options is Arsenic and Antimony. Metalloids are elements that show properties of both metals and non metals. 🔎 The commonly accepted metalloids are: Boron (B), Silicon (Si), Arsenic (As), Antimony (Sb), Tellurium (Te), Germanium (Ge), and sometimes Astatine (At).
29. Which one of the following is the formula of superoxides of alkaline earth metals (M)?
🔎 Superoxides are compounds where oxygen exists in the –1 oxidation state containing Superoxide ion = O₂²⁻. 🔎 Alkaline earth metals of Group IIA (Be, Mg, Ca, Sr, Ba) are divalent cations (M²⁺). 👉 To balance charge with superoxide O₂⁻: M²⁺ + 2(O₂⁻) ⇒ MO₂. So the formula of superoxide for alkaline earth metals is MO₂
30. The element with atomic number 9 is closest to in chemical properties with element of Z:
🔎 Elements of same group or diagonal members have same chemical properties due to identical valence shell electronic configuration and same charge density respectively. 🔎 Atomic number 9 → Fluorine (F). Fluorine belongs to Group VIIA or group 17 (halogens). Halogens share similar chemical properties (form halides, strong oxidizing tendencies, diatomic molecules). 👉 Fluorine is a halogen, so the element closest in chemical properties among the options must be another halogen which is Iodine (Z = 53).
31. The Hybridization in the Carbon atom of Carbonyl group in aldehydes and ketones is
🔎 A carbonyl group is C=O. The carbon atom is double bonded to oxygen and also bonded to two other atoms/groups (depending on whether it’s in aldehyde, ketone, etc.).
🔎 Carbon forms three sigma bonds (two with substituents, one with oxygen).
🔎 One unhybridized p orbital overlaps with oxygen’s p orbital to form the π bond.
👉 So the carbon uses sp² hybridization (three hybrid orbitals + one unhybridized p orbital).
32. The formula for valeric acid is:
👉 Valeric acid = pentanoic acid → 5 carbons total (CH₃ + (CH₂)₃ + COOH).
33. This is the type formula for Ketones.
👉 Ketones have a carbonyl group (C=O) bonded to two alkyl groups (R) with type Formula R–CO–R.
34. Only this one of the compound given below obeys Markownikoff rule on reaction with HCl:
🔎 Markownikoff’s rule states that in addition of HX to an unsymmetrical alkene, H attaches to the carbon with more hydrogens, and X attaches to the carbon with fewer hydrogens. 👉 Propene (CH₃–CH = CH₂) is an unsymmetrical alkene, so HCl adds by Markownikoff’s rule → major product is 2 chloropropane (CH₃–CHCl–CH₃.).
35. Which one of the following is NOT the general formula of carbonyl compounds?
🔎 Carbonyl compounds include aldehydes and ketones → general formula CₙH₂ₙO.
🔎 (c) (CₙH₂ₙ+₁)₂CO → also represents ketones.
🔎 (d) CₙH₂ₙ+₂CO → represents aldehydes.
🔎 (a) CₙH₂ₙO₂ → represents carboxylic acids/esters, not carbonyl compounds.
👉 (a) CₙH₂ₙO₂: This is the formula of carboxylic acids/esters, not aldehydes or ketones.
36. Another name for methane is
👉 Methane (CH₄) is commonly called marsh gas because it is produced naturally by anaerobic decomposition of organic matter in marshes and swamps.
37. Which one of the following formula represents acid halides?
👉 Acid halides are carboxylic acid derivatives with –OH replaced by halogen (X) with type formula R–CO–X (RCOX).
38. The general formula of akanoic acids is:
👉 Alkanoic acids = carboxylic acids (R–COOH) have general formula CₙH₂ₙO₂.
🔎 CₙH₂ₙO → aldehydes/ketones.
🔎 CₙH₂ₙ+₂O₂ → not valid.
🔎 CₙH₂ₙX₂ → dihalides).
39. Anti-knocking character of gasoline is improved by the addition of:
👉 Anti knocking agents prevent premature ignition in gasoline engines thereby reducing knocking. The classic additive used was tetraethyl lead (Pb(C₂H₅)₄). 👉 Other ethyl lead derivatives are not effective or stable for this purpose.
40. A carbon atom having a positive charge is called:
👉 A carbon atom with a positive charge is called a carbocation or carbonium ion. 👉 Carbanion → carbon with a negative charge. 👉 Arenium ion → intermediate in electrophilic substitution of aromatic rings.
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