BPSC EVERYDAY SCIENCE 25 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
زیادہ سے زیادہ قابل اجازت حد جو پیمائش حقیقی قدر سے مختلف ہوسکتی ہے اسے ____ کہا جاتا ہے؟
- Least error
- Permissible error
- Expected error
- None of these
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Explanation
Permissible error defines the tolerance allowed in a measurement.
Ensures accuracy and reliability in engineering measurements.
Permissible error = allowed deviation from true value.
- A mathematical formula
- A physical property of the material
- A configuration for heat conduction
- None of these
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Explanation
Thermal diffusivity indicates how quickly heat spreads through a material.
It depends on thermal conductivity, density, and specific heat of the material.
Thermal diffusivity is an intrinsic physical property of a material.
گیس ٹربائن بلیڈ کاسٹ کرنے کے لئے _____ استعمال کیا جاتا ہے؟
- Investment moulding
- Sand casting
- Die casting
- None of these
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Explanation
Gas turbine blades require very high dimensional accuracy and smooth surface finish.
Investment moulding (lost wax process) is ideal for producing complex and precise shapes.
Gas turbine blades are cast by investment moulding due to high precision requirements.
کاسٹنگ کے لئے سب سے زیادہ استعمال ہونے والی دھات کون سی ہے؟
- Cast iron
- Aluminum
- Brass
- Magnesium alloys
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Explanation
Cast iron has excellent fluidity, allowing it to fill moulds easily.
It is economical and widely used for machine parts, pipes, and engine blocks.
Cast iron is the most commonly used metal for casting.
پرچی اور رینگنے کا مشترکہ اثر ____ سے زیادہ نہیں ہونا چاہئے؟
- 4%
- 1.5%
- 2.5%
- None of these
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Explanation
In belt drives, slip and creep cause a reduction in velocity ratio between driver and driven pulleys.
For efficient power transmission, their combined effect is usually limited to about 4%.
Slip + creep together should not exceed 4% in belt drives.
ریویٹس کو عام طور پر کس بنیاد پر مخصوص کیا جاتا ہے؟
- Shape of head
- Diameter of head
- Diameter of shank
- None of these
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Explanation
Rivets are specified mainly by the diameter of their shank, which determines strength and load-carrying capacity.
Length is selected separately based on plate thickness and head formation.
Rivet size is identified by shank diameter.
کے عمل سے اسٹیل کو جلدی سے سخت کیا جاسکتا ہے؟ _____
- Carbonizing
- Induction hardening
- Nitriding
- None of these
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Explanation
Induction hardening uses high-frequency alternating current to heat the steel surface rapidly.
Immediate quenching produces a hard surface layer in a very short time.
Induction hardening is the fastest surface-hardening process.
کاربن اسٹیل میں ، سلفر کی تھوڑی مقدار میں موجودگی میں ____ بہتر ہوتا ہے؟
- Machinability
- Weldability
- Formability
- None of these
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Explanation
Sulphur forms manganese sulphide inclusions that act as chip breakers during machining.
This reduces cutting resistance and tool wear.
Sulphur is added to carbon steel to improve machinability.
- Resilient
- Tough
- Wear resistant
- None of these
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Explanation
Cast iron contains graphite, which provides good resistance to wear and abrasion.
It is commonly used in machine beds, cylinders, and pipes where wear resistance is required.
Cast iron is known for excellent wear resistance but low ductility.
دھماکے کی بھٹی سے سلیگ ______ پر مشتمل ہے؟
- Calcium and ferrous silicates
- Aluminum and ferrous silicates
- Calcium and aluminum
- None of these
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Explanation
In a blast furnace, limestone decomposes to form calcium oxide, which reacts with silica to form calcium silicate slag.
This slag floats over molten iron and removes impurities efficiently.
Blast furnace slag is mainly composed of calcium silicates.
