इन्जिनियरिङ प्रवेश – Mathematics, Physics, Chemistry, English
इन्जिनियरिङ प्रवेश – Mathematics, Physics, Chemistry, English
Engineering Entrance – Mathematics, Physics, Chemistry & English · ३,८४१ प्रश्न
३,८४१ प्रश्न उपलब्ध। मोड छान्नुहोस्:
इन्जिनियरिङ प्रवेश: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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Which of the following logic gates is a universal gate?
सही उत्तर: घ) NAND
Any logic gate can be built using only NAND gates (or only NOR gates). OR, AND and XOR alone cannot produce all functions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Zener diode is mainly used as a:
सही उत्तर: ग) Voltage regulator
Operated in reverse breakdown, a Zener diode keeps the voltage across it almost constant despite changes in current. A transistor, not a Zener, is used as an amplifier.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The majority charge carriers in an n-type semiconductor are:
सही उत्तर: ख) Electrons
Pentavalent donor atoms contribute extra free electrons, which become majority carriers. Holes are the minority carriers in n-type material.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A p-type semiconductor is formed by doping pure silicon with a:
सही उत्तर: क) Trivalent impurity such as boron
Trivalent atoms create holes (acceptors), making holes the majority carriers. Pentavalent dopants give n-type semiconductors.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Nuclear fission of uranium-235 in a reactor is initiated by:
सही उत्तर: घ) Slow (thermal) neutrons
U-235 has a large fission cross-section for slow neutrons, which is why reactors use moderators. Fission releases about 200 MeV per nucleus.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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X-rays were discovered by:
सही उत्तर: ग) Wilhelm Röntgen
Röntgen discovered X-rays in 1895 while working with cathode-ray tubes. Becquerel discovered radioactivity in 1896.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The function of a moderator in a nuclear reactor is to:
सही उत्तर: ख) Slow down fast neutrons
Moderators like heavy water or graphite slow neutrons so they can efficiently cause fission of U-235. Absorbing neutrons is the job of control rods (e.g. cadmium, boron).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Cathode rays consist of:
सही उत्तर: क) Electrons
J. J. Thomson showed that cathode rays are streams of negatively charged particles, later called electrons, as they are deflected by electric and magnetic fields.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In β⁻ decay, the atomic number and mass number of the nucleus respectively:
सही उत्तर: घ) Increase by 1 and remain unchanged
A neutron changes into a proton emitting an electron (and an antineutrino), so Z increases by 1 while A stays the same. Decrease by 2 and 4 describes alpha decay.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An alpha particle is:
सही उत्तर: ग) A helium nucleus
An alpha particle consists of 2 protons and 2 neutrons (⁴₂He nucleus). A beta particle is an electron, and a gamma ray is a photon.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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