Chapter 17: Group 2 Elements — Topic-wise MCQs
Topic 17.1 — Properties Aur Trends (Q1–12)
- Q1: Group 2 elements s-block mein aate hain (outer electron s-orbital mein hota hai)
- Q2: General electron config: ns² (jaise Ca: [Ar]4s²) — (sahi answer ns² hai, na ke ns¹)
- Q3: Magnesium ka atomic number: 12
- Q4: Group 2 mein sabse zyada melting point: Be (1287°C) (chota size, mazboot metallic bonding)
- Q5: Sabse bara atomic radius: Ba (222 pm)
- Q6: First ionization energy group mein neeche jaate hue kam hoti hai (kyunke size barhta hai)
- Q7: Electrode potential (E°) neeche jaate hue zyada negative hota hai (Be:−1.97V → Ba:−2.91V)
- Q8: Reactivity ka sahi order: Be < Mg < Ca < Sr < Ba (barhta hua)
- Q9: Ca²⁺ ka ionic radius: ≈99 pm
- Q10: Electronegativity neeche jaate hue kam hoti hai (1.5 for Be → 0.9 for Ba)
- Q11: Melting point/density ka trend metal atoms ke different packing se related hai
- Q12: Sabse zyada density: Ba (kyunke mass, volume ke muqablay mein zyada barh jata hai)
Yaad rakho: Group mein neeche jaate hue — size barhta hai, ionization energy kam hoti hai, reactivity barhti hai.
Topic 17.2.1 — Oxygen Ke Saath Reactions (Q13–23)
- Q13: General equation: 2M + O₂ → 2MO
- Q14: Be sirf 600°C se upar oxygen se react karta hai
- Q15: Be+O₂ se milne wala oxide: BeO (BeO2 nahi, ye simple MO form hai)
- Q16: Mg jalta hai bright white flame ke saath
- Q17: Ca jalta hai brick-red flame ke saath
- Q18: Group 2 oxides generally basic hote hain
- Q19: Basic character neeche jaate hue barhta hai
- Q20: Oxide ion + paani → OH⁻ ions banate hain
- Q21: Be kam reactive isliye hai kyunke iska thin, strong protective oxide layer banta hai
- Q22: Sabse kam reactive (protective layer ki wajah se): Be
- Q23: 2Be+O₂ → 2BeO
Topic 17.2.2 — Water Ke Saath Reactions (Q24–33)
- Q24: Paani/steam se bilkul react na karne wala: Be
- Q25: Mg cold water se banata hai: Mg(OH)₂ aur H₂
- Q26: Mg steam se banata hai: MgO aur H₂
- Q27: Ca paani se banata hai: Ca(OH)₂ aur H₂
- Q28: Ca(OH)₂ ki solubility: Sparingly soluble (isliye white precipitate dikhta hai)
- Q29: Cold water se zyada vigorously react karta hai: Calcium (Mg se zyada)
- Q30: Be paani se react nahi karta kyunke iska strong oxide layer protect karta hai
- Q31: Group 2 hydroxides ki basic character neeche jaate hue barhti hai
- Q32: Group 1 hydroxides ke muqablay mein Group 2 hydroxides kam basic hote hain
- Q33: Group 2 metals paani se react karne par nikalne wali gas: Hydrogen
Topic 17.2.3 — Acids Ke Saath Reactions (Q34–43)
- Q34: General equation: M + 2HCl → MCl₂ + H₂
- Q35: Be dilute acids se dheere react karta hai (protective oxide layer ki wajah se)
- Q36: Mg + dilute HCl → MgCl₂ aur H₂
- Q37: Mg + dilute H₂SO₄ → MgSO₄ aur H₂
- Q38: Ca ki H₂SO₄ ke saath reaction jaldi rukti hai kyunke CaSO₄ metal surface ko coat kar leta hai
- Q39: Ca + dilute HCl → CaCl₂ aur H₂
- Q40: Reactivity dilute acids ke saath group mein neeche jaate hue barhti hai
- Q41: Acid ke saath react karne par nikalne wali gas: Hydrogen
- Q42: Ca ki H₂SO₄ reaction rokne wala sparingly soluble salt: CaSO₄
- Q43: Be ki acid reaction dheeme hone ki wajah: protective oxide layer acid ke attack ko slow karti hai
Topic 17.3 — Group 2 Vs Group 1 Comparison (Q44–54)
- Q44: Group 1 ke valence electrons: 1
- Q45: Group 2 ke valence electrons: 2
- Q46: Group 1 ions ka charge: +1
- Q47: Group 2 ions ka charge: +2
- Q48: Same period mein zyada reactive: Group 1
- Q49: Group 1 metals generally Group 2 se naram (softer) hote hain
- Q50: Group 1 metal oxide ka formula: M₂O
- Q51: Group 2 metal oxide ka formula: MO
- Q52: Zyada soluble aur mazboot bases wale hydroxides: Group 1
- Q53: Group 2 metals ke melting/boiling points Group 1 se generally: Higher (zyada)
- Q54: Group 1 zyada reactive isliye hai kyunke unki ionization energy kam hoti hai (sirf ek electron nikalna hai)
Topic 17.4 — Carbonates Aur Nitrates Ki Thermal Decomposition (Q55–66)
- Q55: Thermal decomposition reactions generally endothermic hoti hain
- Q56: Group 2 carbonates heat hone se: Metal oxide + CO₂
- Q57: Sabse kam temperature par decompose hone wala carbonate: BeCO₃ (250°C)
- Q58: Sabse zyada temperature chahiye: BaCO₃ (1360°C)
- Q59: CaCO₃ ka decomposition temperature: ≈900°C
- Q60: MgCO₃ ka decomposition temperature: ≈540°C
- Q61: Group 2 nitrates heat hone se: Metal oxide, NO₂, aur O₂
- Q62: Nitrates ki thermal stability group mein neeche jaate hue: Barhti hai (increases)
- Q63: Sabse zyada polarizing power: Be²⁺ (sabse chota cation)
- Q64: Zyada polarizing power se carbonate ki thermal stability: Kam ho jaati hai
- Q65: Thermal stability mainly related hai: Cation ki polarizing power se
- Q66: Barhta hua thermal stability order: BeCO₃ < MgCO₃ < CaCO₃ < SrCO₃ < BaCO₃
Yaad rakho: Chota cation = zyada polarizing power = anion zyada distort = kam thermal stability.
Topic 17.5 — Sulphates Aur Hydroxides Ki Solubility (Q67–78)
- Q67: Enthalpy of hydration hamesha: Exothermic
- Q68: Lattice enthalpy hamesha: Endothermic
- Q69: Group 2 hydroxides ki solubility neeche jaate hue: Barhti hai (increases)
- Q70: Group 2 sulphates ki solubility neeche jaate hue: Ghatti hai (decreases)
- Q71: Sabse zyada soluble hydroxide: Ba(OH)₂
- Q72: Sabse kam soluble sulphate: BaSO₄
- Q73: Enthalpy of solution = Lattice enthalpy + Hydration enthalpy
- Q74: Zyada negative enthalpy of solution → zyada solubility
- Q75: Hydroxides ke liye: Lattice enthalpy hydration enthalpy se zyada tezi se girti hai
- Q76: Sulphates ke liye: Hydration enthalpy lattice enthalpy se zyada tezi se girti hai
- Q77: Mg(OH)₂ ki solubility (298K): ≈2×10⁻⁴ mol/100g (values approximate, apni book se confirm karein)
- Q78: BaSO₄ ki solubility (298K): ≈9.43×10⁻⁶ mol/100g
Yaad rakho: Chota anion (OH⁻) → lattice enthalpy hawi → solubility barhti hai. Bara anion (SO₄²⁻) → hydration enthalpy hawi → solubility ghatti hai.
Topic 17.6 — Complex Ion Formation (Q79–89)
- Q79: Complex ion mein central metal ion juda hota hai: Electron-donating species (ligands) se
- Q80: Central metal ion kaam karta hai: Lewis acid ki tarah
- Q81: Coordinate bonds ki tadaad kehlati hai: Coordination number
- Q82: Common coordination numbers: 2, 4, 6
- Q83: Be ka hydrated complex ion coordination number: 4
- Q84: Mg ka hydrated complex ion coordination number: 6
- Q85: Be ka hydrated complex formula: [Be(H₂O)₄]²⁺
- Q86: Mg ka hydrated complex formula: [Mg(H₂O)₆]²⁺
- Q87: EDTA, Ca ke saath ring complex banata hai: 6 donor sites se
- Q88: Ca-EDTA complex use hota hai: Water softening mein
- Q89: Complex banane ki ability depend karti hai: Size aur charge (charge density) par
Topic 17.7 — Extraction Aur Purification (Q90–101)
- Q90: Magnesium seawater se nikala jata hai: Dow Process se
- Q91: Dow Process mein Mg pehle precipitate hota hai: Mg(OH)₂ ki soorat mein
- Q92: Dow Process ka Ca(OH)₂ nikalta hai: Limestone ya oyster shells se
- Q93: Mg(OH)₂ ko react karaya jata hai: HCl ke saath
- Q94: Dow Process ka aakhri step: Molten MgCl₂ ki electrolysis
- Q95: Electrolysis mein Mg metal banta hai: Cathode par
- Q96: Electrolysis mein Cl₂ gas banti hai: Anode par
- Q97: Quicklime banti hai heat kar ke: CaCO₃ (limestone) ko
- Q98: Quicklime banane ki furnace kehlati hai: Lime kiln
- Q99: Quicklime banane ka temperature range: 900-1000°C
- Q100: CO₂ ko musalsal hataya jata hai taake: Equilibrium right taraf shift ho aur production tez ho
- Q101: Limestone heat karne ka process kehlata hai: Calcination (thermal decomposition)
Topic 17.8 — Group 2 Compounds Ke Uses (Q102–113)
- Q102: CaCO₃ prakritik tor par milta hai: Limestone, marble, aur chalk ki soorat mein
- Q103: CaO/Ca(OH)₂ use hote hain: Cement, mortar, plaster banane mein
- Q104: Gypsum ka formula: CaSO₄·2H₂O
- Q105: Flue gas desulphurization mein use hone wale compounds: CaO aur CaCO₃
- Q106: MgO refractory material isliye hai kyunke iska: High melting point hai
- Q107: “Milk of Magnesia” hai: Mg(OH)₂
- Q108: Mg(OH)₂ medically use hota hai: Antacid aur mild laxative ki tarah
- Q109: BaSO₄ use hota hai: ‘Barium meals’ X-ray imaging ke liye
- Q110: BaSO₄ jism ke andar safe isliye hai kyunke ye: Highly insoluble hai
- Q111: Epsom salts ka formula: MgSO₄·7H₂O
- Q112: CaCO₃/Ca(OH)₂ acidic soil mein daale jate hain taake: Excess acidity neutralize ho aur pH barhe
- Q113: Chlorophyll ka central atom (photosynthesis ke liye zaroori): Magnesium
Sabse Zaroori Formulas Aur Facts Jo In MCQs Mein Ghoomte Rahe:
| Concept | Yaad Rakhne Wali Baat |
|---|---|
| Electron config | ns² |
| Reactivity order | Be<Mg<Ca<Sr<Ba (barhta hua) |
| Thermal stability order | BeCO₃<MgCO₃<CaCO₃<SrCO₃<BaCO₃ (barhta hua) |
| Hydroxide solubility | Neeche jaate hue barhti hai |
| Sulphate solubility | Neeche jaate hue ghatti hai |
| Be complex | [Be(H₂O)₄]²⁺ (coordination 4) |
| Mg complex | [Mg(H₂O)₆]²⁺ (coordination 6) |
Exam Tip: In MCQs mein zyada tar sawalat trends aur specific facts/values (temperatures, formulas) test karte hain — inhe table ki soorat mein yaad karna sabse aasan tareeqa hai.