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Chemistry · Structure of atom
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Chemistry · Structure of atom
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The energy of an electron in a hydrogen atom has a negative sign for all possible orbits. Reason (R): This negative sign means that the energy of the electron in the atom is lower than the energy of a free electron at rest. In the light of the above statements, choose the correct answer from the options given below:
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Consider the following statements regarding the characteristics of black body radiation: (A) A black body is a perfect radiator and perfect absorber of radiant energy. (B) The amount of light emitted and its spectral distribution depend only on its temperature. (C) At a given temperature, intensity of radiation emitted increases with increase of wavelength, reaches a maximum, and then decreases. (D) Carbon black approximates fairly closely to a black body. Which of the above statements are correct?
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Isotopes of an element show identical chemical behavior. Reason (R): Chemical properties are dictated by the number of electrons, which depend on the nuclear proton count. In the light of the above statements, choose the correct answer from the options given below:
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The charge to mass ratio of particles in canal rays depends on the nature of the gas present in the discharge tube. Reason (R): Canal rays are positively charged gaseous ions derived from the gas inside the discharge tube. In the light of the above statements, choose the correct answer from the options given below:
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Calculate the de Broglie wavelength of an electron moving with a velocity of \( 2.05 \times 10^7 \text{ m s}^{-1} \). (Mass of electron \( = 9.1 \times 10^{-31} \text{ kg} \))
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Calculate the wavelength of an electron with kinetic energy \( 3.0 \times 10^{-25} \text{ J} \). (Mass of electron \( = 9.1 \times 10^{-31} \text{ kg} \))
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What is the SI unit of frequency \( \nu \)?
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Calculate the de Broglie wavelength of an electron moving with a velocity of \( 1.0 \times 10^7 \text{ m s}^{-1} \) (mass of electron \( m_e = 9.1 \times 10^{-31} \text{ kg} \), \( h = 6.626 \times 10^{-34} \text{ J s} \)).
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The volume occupied by the nucleus is negligibly small as compared to the total volume of the atom. Reason (R): The radius of an atom is about \( 10^{-10} \text{ m} \), whereas the radius of a nucleus is about \( 10^{-15} \text{ m} \). In the light of the above statements, choose the correct answer from the options given below:
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Calculate the energy of one mole of photons of radiation whose frequency is \( 5 \times 10^{14}\text{ Hz} \). (Given \( h = 6.626 \times 10^{-34}\text{ J s} \), \( N_A = 6.022 \times 10^{23}\text{ mol}^{-1} \))
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Which of the following configurations possesses extra stability due to symmetrical distribution and exchange energy?
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A 100 watt bulb emits monochromatic light of wavelength \( 400 \text{ nm} \). Calculate the number of photons emitted per second by the bulb.
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Which of the following spectral series of hydrogen atom lie in the infrared region according to Table 2.3? (A) Lyman series (B) Balmer series (C) Paschen series (D) Brackett series (E) Pfund series Choose the correct answer from the options given below:
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Given below are two statements:\n Statement I: The energy of an orbital in a multi-electron atom depends on both principal quantum number \( n \) and azimuthal quantum number \( l \).\n Statement II: According to the Aufbau principle, orbitals are filled in order of increasing energy determined by the \( (n + l) \) rule. \nIn the light of the above statements, choose the most appropriate answer from the options given below:
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Given below are two statements: Statement I: The mass of an electron is about \( 9.109382 \times 10^{-31} \text{ kg} \), which is roughly 1/1836th of a proton mass. Statement II: Neutrons are electrically neutral particles with a mass slightly less than that of protons. In the light of the above statements, choose the most appropriate answer from the options given below:
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): An electron can move only in those orbits for which its angular momentum is an integral multiple of \( \frac{h}{2\pi} \). Reason (R): Maxwell's electromagnetic theory allows electrons to move in any arbitrary orbit around the nucleus without radiating energy. In the light of the above statements, choose the correct answer from the options given below:
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Which of the following spectral series of atomic hydrogen falls entirely in the ultraviolet region?
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Match List-I with List-II: List-I List-II A James Clerk Maxwell I Photoelectric effect explanation B Max Planck II Electromagnetic radiation theory C Albert Einstein III Quantum theory of radiation D Heinrich Hertz IV Discovery of photoelectric current Choose the correct answer from the options given below:
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A microscope using suitable photons is employed to locate an electron in an atom within a distance of \( 0.1 \text{ \AA} \). What is the uncertainty involved in the measurement of its velocity (\( \Delta v \))?
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Calculate the number of neutrons in the species \( {}_{35}^{80}\text{Br} \).
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Consider the following statements regarding the characteristics of orbitals and wave functions:\n(A) The probability density \( |\psi|^2 \) is always positive.\n(B) For \( 1s \) orbital, the probability density is maximum at the nucleus and decreases sharply as we move away from it.\n(C) Boundary surface diagrams for three \( 2p \) orbitals are spherical in shape.\n(D) The number of nodal surfaces for \( ns \)-orbital is equal to \( n - 1 \). \nWhich of the above statements are correct?
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Consider the following statements regarding Bohr's model for the hydrogen atom: (A) The electrons move around the nucleus in circular paths of fixed radius and energy called orbits. (B) The frequency of radiation emitted or absorbed is given by \( \nu = \frac{E_2 - E_1}{h} \). (C) The angular momentum of an electron is quantized: \( m_e v r = n \frac{h}{2\pi} \). (D) The energy of an electron in an orbit is directly proportional to \( n^2 \). Which of the above statements are correct?
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