JST PAST PAPER 11-04-2026
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
ہر ایٹم کے نیوکلئس میں موجود پروٹانس کی مخصوص تعداد اس کو ____ کہتے ہیں؟
- Atomic Number
- Mass Number
- Atomic Mass
- Valance Number
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Every element is identified by the number of protons in its nucleus.
- This number determines the identity of the element.
- It is written as Z in chemistry.
- It is always equal to the number of electrons in a neutral atom.
- This is called the atomic number.
Last verified on 12-04-2026
ریڈیو ایکٹو نیوکلیائی کے آدھے حصے کے ختم ہونے میں لگنے والا وقت کیا کہلاتا ہے؟
- Lifetime
- Mean life
- Half-life
- None of these
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Explanation
- Radioactive substances decay over time in a predictable pattern.
- The time required for half of the radioactive nuclei to decay is a standard measure.
- It is used to compare stability of different radioactive elements.
- This concept is widely used in nuclear physics and medicine.
- It is called the half-life of a substance.
Last verified on 12-04-2026
مندرجہ ذیل میں سے کون سا لینس خوردبین میں استعمال ہوتا ہے؟
- Concave Lens
- Curved Lens
- Convex Lens
- None of these
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Explanation
- A simple microscope is used to magnify small objects.
- It works by bending light to produce a larger image.
- Only a converging lens can produce a magnified virtual image.
- A convex lens has this property.
- Therefore, simple microscopes use a convex lens.
Last verified on 12-04-2026
مقررہ کمیت والی گیس کے لیے جب دباؤ مستقل ہو تو اس کا حجم مطلق درجہ حرارت کے متناسب ہوتا ہے۔ یہ کس قانون کو ظاہر کرتا ہے؟
- Avogadro's law
- Boyle's law
- Charles law
- None of these
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Explanation
- When pressure is constant, the volume of a gas changes directly with temperature (in Kelvin).
- As temperature increases, gas particles move faster and occupy more space.
- This relationship is used to describe gas expansion.
- It applies only at constant pressure conditions.
- This is known as Charles’s Law.
Last verified on 12-04-2026
ایٹم کے نیوکلئس کو چھوٹے یونٹوں میں تقسیم کرنے کا عمل کیا ہے؟
- Fusion
- Dillusion
- Fission
- Diffusion
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Explanation
- Fission is the process of splitting an atomic nucleus into smaller nuclei, releasing a large amount of energy.
- It is used in nuclear power plants and atomic bombs.
Last verified on 12-04-2026
اگر کسی موج کی فریکوئنسی کو دوگنا کر دیا جائے (رفتار مستقل ہو)، تو اس کی طولِ موج کیا ہو گی؟
- Zero
- Unchanged
- Halved
- None of these
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Explanation
- Wave speed is given by v = fλ.
- If speed remains constant, frequency and wavelength are inversely related.
- So, when frequency increases, wavelength decreases.
- If frequency is doubled, wavelength becomes half.
- This is a basic wave relation in physics.
Last verified on 12-04-2026
جسمانی مقدار ورک (کام) کی ڈائمینشنس کیا ہیں؟
- ML²T⁻²
- M²LT⁻²
- ML²T²
- None of these
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Explanation
- Work is defined as force × displacement.
- Force has dimensions MLT⁻².
- Displacement has dimension 𝐿.
- So, work = MLT⁻² × 𝐿 = ML²T⁻².
Last verified on 12-04-2026
ہیبر پروسیس کے ذریعے امونیا کی تیاری کے بارے میں کون سا بیان درست ہے؟
- The reactants are both obtained from the air
- The reactants and product are elements
- The reactants and product are gases
- None of these
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Explanation
- Haber process is used to manufacture ammonia from nitrogen and hydrogen.
- Nitrogen is obtained from air, but hydrogen is usually obtained from natural gas or water, not both from air.
- Ammonia is formed as a compound.
- The reaction involves gases under high pressure and temperature.
- Therefore, the correct statement is about physical state of reactants and product.
Last verified on 12-04-2026
- Burette, Pipette, Thermometer
- Balance, Measuring Cylinder, Thermometer
- Balance, Pipette, Thermometer
- Balance, Pipette, Stopwatch
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Explanation
- To obtain accurate results, precise measurement of mass and volume is essential.
- A balance is used to measure 2.5 g sodium carbonate accurately.
- A pipette measures 25.0 cm³ acid more accurately than a measuring cylinder.
- A thermometer is needed to record temperature change.
- Therefore, these three give the most accurate results.
Last verified on 12-04-2026
اگر میگنیشیم کی ربن کی بجائے پاؤڈر استعمال کیا جائے تو ہائیڈروکلورک ایسڈ کے ساتھ ردِعمل کی رفتار پر کیا اثر ہوگا؟
- The rate would decrease
- No effect on the rate
- The rate would increase
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Powdered magnesium has a much larger surface area compared to magnesium ribbon.
- A greater surface area allows more collisions between magnesium and hydrochloric acid particles.
- This increases the frequency of successful collisions.
- Therefore, the reaction rate increases.
- So, powdered magnesium reacts faster than ribbon.
Last verified on 12-04-2026
