JST 5 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
مندرجہ ذیل میں سے کون سا غیر جانبدار نمک کی مثال ہے؟
- NaCl
- Na₂CO₃
- NH₄Cl
- CH₃COONa
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- A neutral salt is formed when a strong acid reacts with a strong base.
- It does not show acidic or basic nature in water.
- Its pH is approximately 7.
- It contains equal strength of acid and base ions.
- Example of neutral salt is NaCl (Sodium Chloride).
Last verified on 11-04-2026
- 52g
- 48g
- 104g
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
To get max Cr from Cr₂O₃, use the mass fraction of Cr in Cr₂O₃.
Molar mass Cr₂O₃ = 2(52) + 3(16) = 104 + 48 = 152 g/mol
Mass of Cr in 1 mol = 2(52) = 104 g
So Cr mass = 76g × (104/152) = 76 × 0.684 = 52g
Last verified on 11-04-2026
فوسل فیول جلانے سے حرارتی توانائی پیدا ہوتی ہے۔ درج ذیل میں سے کون سا فوسل فیول نہیں ہے؟
- Coal
- Petroleum
- Natural gas
- Hydrogen
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Coal, petroleum, and natural gas are fossil fuels formed from ancient organic matter.
- Hydrogen is a clean fuel, not formed from fossilized remains.
- It is considered a future energy source due to its high efficiency and low pollution.
Last verified on 11-04-2026
جب مرتکز آبی سوڈیم کلورائیڈ میں برقی رو گزاری جائے اور غیر فعال الیکٹروڈ استعمال ہوں تو منفی الیکٹروڈ پر کیا بنتا ہے؟
- Chlorine
- Sodium
- Hydrogen
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Electrolysis of concentrated aqueous sodium chloride (brine) involves breaking down compounds using electricity.
- Inert electrodes do not take part in the reaction.
- At the negative electrode (cathode), reduction occurs.
- Hydrogen ions are reduced instead of sodium ions in aqueous solution.
- This produces hydrogen gas at the cathode.
Last verified on 11-04-2026
کیا تھرموڈائنامک نظام میں کیا گیا کام ایک اسٹیٹ فنکشن ہے؟
- False
- True
- Only sometimes
- None of these
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Explanation
- In thermodynamics, state functions depend only on initial and final states.
- They do not depend on the path taken.
- Examples include internal energy, enthalpy, and entropy.
- Work done depends on the path of the process.
- Therefore, it is not a state function.
Last verified on 11-04-2026
نمک اور پانی کے مرکب کو الگ کر کے دونوں اجزاء حاصل کرنے کے لیے کون سا طریقہ استعمال کیا جاتا ہے؟
- Evaporation
- Distillation
- Crystallization
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- A salt and water mixture is a homogeneous solution.
- To separate both components, we need a method that recovers water and salt separately.
- Some methods only recover one component.
- Proper separation depends on physical properties like boiling point.
- Distillation is used for complete separation of both substances.
Last verified on 11-04-2026
مناسب درجہ حرارت سے زیادہ درجہ حرارت انزائم کی کارکردگی کیوں کم کر دیتا ہے؟
- It accelerates substrate product complex formation
- It increases substrate bonding
- It alters the enzyme's structure
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Enzymes work best at an optimum temperature.
- Temperature changes affect enzyme activity and shape.
- High temperature can damage enzyme structure.
- This reduces the enzyme’s ability to function properly.
- Enzymes are sensitive biological catalysts.
Last verified on 11-04-2026
پیشاب کے اخراج کا درست ترتیب کیا ہے؟
- Kidney → Urethra → Urinary Bladder → Ureter
- Kidney → Ureter → Urinary Bladder → Urethra
- Kidney → Urinary Bladder → Ureter → Urethra
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
The human urinary system functions as a sequence of organs that filter blood and eliminate waste in a specific order:
- Kidney: The starting point where blood is filtered and urine is formed.
- Ureter: Narrow, tubular structures that transport the formed urine from the kidneys down to the bladder.
- Urinary Bladder: A muscular sac in the pelvic cavity that acts as a temporary storage reservoir for urine.
- Urethra: The final canal-shaped tube through which urine is expelled from the body to the exterior.
Last verified on 11-04-2026
صحرا کے ماحولیاتی نظام میں ثانوی صارفین (سانپوں) کی آبادی کم ہو جائے تو اس کا سب سے ممکنہ نتیجہ کیا ہوگا؟
- Termination of the population of primary consumers
- Increase in the population of primary consumers
- Decrease in the population of primary consumers
- None of these
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Explanation
- Snakes normally control the population of primary consumers.
- When snakes decrease, predation pressure reduces.
- As a result, primary consumers (like rodents, insects) increase.
- This can disturb ecological balance in the desert ecosystem.
Last verified on 11-04-2026
ایک نوزائیدہ بچے میں ڈاؤن سنڈروم کی رپورٹ میں گیمیٹس کی تشکیل میں غلطی ظاہر ہوئی ہے۔ یہ حالت کس وجہ سے پیدا ہوتی ہے؟
- Alternation in cell division checkpoints
- Improper segregation of homologous chromosomes
- Crossing over between non-sister chromatids
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- This condition is caused by nondisjunction during meiosis.
- Homologous chromosomes fail to separate properly in meiosis I (or sister chromatids in meiosis II).
- As a result, one gamete gets an extra chromosome.
- After fertilization, this leads to trisomy 21 (Down syndrome).
Last verified on 11-04-2026