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۔
ایک ہی سالماتی فارمولا رکھنے والے مرکبات لیکن مختلف ڈھانچے کو ______ کہا جاتا ہے؟
- Isomers
- Isotopes
- Polymers
- None of these
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Explanation
- Compounds with the same molecular formula but different arrangements of atoms are called isomers.
- Isomers can have different chemical and physical properties despite having the same number of atoms.
Additional information:
- Example of isomers: C₂H₆O → Ethanol (CH₃CH₂OH) and Dimethyl ether (CH₃OCH₃)
- Isomerism is classified into structural isomers and stereoisomers.
Last verified on 20-01-2026
- 8.314 × 10⁷
- 8.314 × 10⁷
- 2.314
- None of these
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Explanation
The gas constant R in ergs mol⁻¹ K⁻¹ is 8.314 × 10⁷.It is derived from the SI value 8.314 J mol⁻¹ K⁻¹, where 1 J = 10⁷ ergs.
امونیا سولوی عمل _____ کی تیاری کے لئے استعمال ہوتا ہے؟
- Potash alum
- Caustic soda
- Washing soda
- None of these
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Explanation
The Solvay process is an industrial method for producing sodium carbonate (washing soda).It involves ammonia, carbon dioxide, and sodium chloride as key reactants.
کسی کمپاؤنڈ کی آپٹیکل سرگرمی کی پیمائش کے لئے مندرجہ ذیل میں سے کون سا آلات استعمال ہوسکتے ہیں؟
- Polarimeter
- Spectrophotometer
- Calorimeter
- None of these
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Explanation
A polarimeter measures the optical activity of a compound by analyzing the rotation of plane-polarized light.Optically active compounds, like chiral molecules, rotate light either clockwise (dextrorotatory) or counterclockwise (levorotatory).
سب سے میٹھی چینی ______ ہے؟
- Glucose
- Sucrose
- Fructose
- None of these
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Explanation
Fructose is the sweetest natural sugar.It is found in fruits, honey, and high-fructose corn syrup.
- Copper and Nikal
- Copper and Tin
- Copper and Steel
- None of these
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Explanation
Bronze is mainly made of copper with about 12–12.5% tin as the primary additive.It is stronger and harder than pure copper, making it useful for tools, weapons, and sculptures.
- Solid oxygen
- Solid Nitrogen
- Solid Carbon dioxide
- None of these
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Explanation
Dry ice is a solid form of carbon dioxide.
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"Dry ice" is solid, frozen carbon dioxide, which is sublimated at a chilly -78.5 °C (-109.3°F).
Dry ice is used primarily as a cooling agent.
Dry ice does not melt into a liquid when heated instead, it changes directly into a gas.
ND16-8-2023
- Increases the average kinetic energy of the reactants
- Alters the reaction mechanism
- Increases the activation energy
- None of these
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Explanation
A catalyst provides an alternative reaction pathway with lower activation energy.It does not change reactants' energy but speeds up the reaction.
- Hydroxyl group
- Benzene ring
- Carbonyl group
- None of these
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Explanation
Phenols contain a hydroxyl (-OH) group attached to a benzene ring.They do not have a carbonyl group (C=O), which is found in aldehydes, ketones, and carboxylic acids.
الکحل اور کاربو آکسیلک ایسڈ کے مابین رد عمل کی پیداوار کو ______ کہا جاتا ہے؟
- Ester
- Amide
- Alkoxide
- None of these
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Explanation
The reaction between an alcohol and a carboxylic acid is called esterification.This reaction produces an ester and water as byproducts.
