SPSC CHEMISTRY 25 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
نیوٹرون کس نے دریافت کیا؟
- Rutherford
- Thomson
- J Perrin
- Chadwick
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Explanation
- Sir James Chadwick discovered the neutron in 1932.
- He was a British physicist.
- His discovery completed the basic picture of the atomic nucleus.
- He received the Nobel Prize in Physics in 1935 for this discovery.
Additional information:
- J. J. Thomson – Electron (1897)
- Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)
Last verified on 03-07-2026
- 0.86
- 1.76
- 0.57
- 5.16
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Explanation
Look at the reaction: N₂ + 3H₂ → 2NH₃
For every 1 N₂ that reacts, 3 H₂ react.
So H₂ gets used 3 times faster than N₂.
Given: H₂ is used at 1.72 mol L⁻¹ h⁻¹
Then N₂ is used 3x slower:
Rate of N₂ = 1.72 ÷ 3 = 0.57 mol L⁻¹ h⁻¹
Last verified on 05-06-2026
طویل ہائیڈروکاربن چین والے کاربوکسلک ایسڈ ہوتے ہیں۔ _____
- Fats
- Lipids
- Fatty acids
- Proteins
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Explanation
- Fatty acids are carboxylic acids with long hydrocarbon chains.
- They contain a carboxyl group (–COOH) attached to a long alkyl chain.
- They are major components of fats and oils.
Last verified on 05-06-2026
ثانوی الکوحل کے آکسیڈیشن سے کیا بنتا ہے؟
- Aldehydes
- Ketones
- Ethers
- Esters
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Explanation
- Oxidation of secondary alcohols produces ketones.
- Secondary alcohols have –OH group attached to a carbon bonded with two other carbons.
- During oxidation, hydrogen is removed and a carbonyl (C=O) group is formed.
Additional information:
- Primary alcohol → Aldehyde → Acid
- Secondary alcohol → Ketone (stops here)
- Tertiary alcohol → No easy oxidation
Last verified on 05-06-2026
کاربنک ایسڈ میں ہر آکسیجن کے بانڈ بنانے میں کاربن کے کون سے ہائبرڈ اوربٹلز استعمال ہوتے ہیں؟
- sp³
- sp²
- sp
- None of these
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Explanation
- sp² hybridization is used by each oxygen in carbonic acid (H₂CO₃).
- In H₂CO₃, carbon is bonded to three oxygen atoms.
- Each oxygen forms sigma bonds and has resonance involvement.
- Oxygen adopts sp² hybrid orbitals for proper bonding geometry.
Last verified on 05-06-2026
وہ عناصر جن کا نیوکلیئر اسپن صفر ہو انہیں براہ راست کس تکنیک سے معلوم نہیں کیا جا سکتا؟
- NMR spectroscopy
- Atomic Absorption spectroscopy
- IR spectroscopy
- HPLC
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Explanation
- NMR (Nuclear Magnetic Resonance) spectroscopy depends on nuclear spin.
- Only nuclei with non-zero spin give NMR signals.
- Elements with zero nuclear spin are NMR inactive.
- Therefore, they cannot be directly detected by NMR spectroscopy.
Last verified on 05-06-2026
- 1500 mol⁻¹ dm³ cm⁻¹
- 1.5 mol⁻¹ dm³ cm⁻¹
- 150 mol⁻¹ dm³ cm⁻¹
- None of these
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Explanation
Use Beer-Lambert Law: A = ε c l
Where:
A = absorbance = 0.15
c = concentration = 1.0 × 10⁻³ mol dm⁻³
l = path length = 1 cm
ε = molar extinction/absorption coefficient = ?
Rearrange: ε = A / (c × l)
ε = 0.15 / (1.0 × 10⁻³ × 1)
ε = 0.15 / 0.001 = 150 mol⁻¹ dm³ cm⁻¹
Last verified on 05-06-2026
فریڈل–کرافٹس الکائلیشن میں استعمال ہونے والا کاتالسٹ کون سا ہے؟
- AlCl₃
- FeCl₃
- Pt
- I₂
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Explanation
- AlCl₃ is the catalyst in Friedel–Crafts alkylation.
- It acts as a Lewis acid and generates the electrophile (R⁺).
- This electrophile attacks benzene ring in the reaction.
Last verified on 05-06-2026
سمندری پانی سے خالص پانی حاصل کرنے کے لیے کون سا طریقہ استعمال کیا جاتا ہے؟
- Filtration
- Chromatography
- Distillation
- Centrifugation
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Explanation
- Pure water can be obtained from seawater by distillation.
- Distillation separates water from dissolved salts and impurities.
- Seawater is heated to form water vapor.
- The vapor is then cooled and condensed into pure water.
- Therefore, distillation gives clean, salt-free water.
Last verified on 05-06-2026
مندرجہ ذیل میں سے کون سا ٹرانزیشن میٹل کمپلیکس نہیں ہے؟
- K₄[Fe(CN)₆]
- K₃[Fe(CN)₆]
- [Ni(H₂O)₆]SO₄
- K₂Cr₂O₇
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Explanation
- K₂Cr₂O₇ (potassium dichromate) is an ionic compound, not a coordination complex.
- It contains Cr in an ionic lattice without ligands forming a complex ion.
- Transition metal complexes contain a central metal ion with ligands.
- K₄[Fe(CN)₆], K₃[Fe(CN)₆], and [Ni(H₂O)₆]SO₄ are all coordination (complex) compounds.
Last verified on 05-06-2026