काठमाडौं विश्वविद्यालय KUUMAT / KU CBT तयारी
काठमाडौं विश्वविद्यालय – KUUMAT / KU CBT
KUUMAT / KU CBT · Kathmandu University (KUUMAT / KU CBT)
३,८४१ प्रश्न उपलब्ध। मोड छान्नुहोस्:
BE/B.Arch 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 pair of atoms are isobars?
सही उत्तर: ख) ⁴⁰Ar and ⁴⁰Ca
Isobars have the same mass number but different atomic numbers, as ⁴⁰Ar (Z = 18) and ⁴⁰Ca (Z = 20) do. ¹²C and ¹⁴C have the same atomic number, so they are isotopes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of unpaired electrons in a nitrogen atom in its ground state is:
सही उत्तर: क) 3
Nitrogen is 1s² 2s² 2p³, and by Hund's rule the three 2p electrons occupy separate orbitals, giving 3 unpaired electrons. Five is the total number of valence electrons, not unpaired ones.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Heisenberg's uncertainty principle, the product Δx·Δp is:
सही उत्तर: घ) ≥ h/4π
Heisenberg's principle states Δx·Δp ≥ h/4π, so position and momentum cannot both be known exactly. The product can never be smaller than h/4π.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which spectral series of the hydrogen atom lies in the visible region?
सही उत्तर: ग) Balmer series
Balmer lines arise from transitions ending at n = 2 and fall in the visible region. The Lyman series (ending at n = 1) lies in the ultraviolet.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The ground-state energy of the electron in a He⁺ ion is:
सही उत्तर: ख) −54.4 eV
For hydrogen-like species Eₙ = −13.6 Z²/n² eV; with Z = 2 and n = 1, E = −13.6 × 4 = −54.4 eV. −27.2 eV results from multiplying by Z instead of Z².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The energy of the electron in the first Bohr orbit of a hydrogen atom is:
सही उत्तर: क) −13.6 eV
Eₙ = −13.6/n² eV, so for n = 1, E = −13.6 eV; the negative sign shows the electron is bound. −3.4 eV is the energy of the second orbit.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In Bohr's model of the hydrogen atom, the radius of the third orbit compared with the first orbit is:
सही उत्तर: घ) 9 times
The Bohr radius is proportional to n², so r₃/r₁ = 3² = 9. Three times would be true only if radius were directly proportional to n.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of unpaired electrons in the Fe³⁺ ion (Fe, Z = 26) is:
सही उत्तर: ग) 5
Fe³⁺ has the configuration [Ar] 3d⁵, with all five d electrons unpaired according to Hund's rule. Four unpaired electrons belong to Fe²⁺ (3d⁶).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The number of orbitals in a subshell with azimuthal quantum number l = 2 is:
सही उत्तर: क) 5
The number of orbitals in a subshell is 2l + 1 = 5 for l = 2 (a d subshell). Three orbitals belong to a p subshell (l = 1).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The total number of atoms present in 0.5 mol of ammonia (NH₃) is approximately:
सही उत्तर: घ) 1.204 × 10²⁴
Each NH₃ molecule has 4 atoms, so atoms = 0.5 × 4 × 6.022 × 10²³ ≈ 1.204 × 10²⁴. 3.011 × 10²³ is only the number of molecules.
💬 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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