41. Which of the following quantum numbers give information about the spatial orientation of the orbital with respect to standard set of co-ordinate axis?
[A] Azimuthal quantum number
[B] Principal quantum number
[C] Magnetic quantum number
[D] Electron spin quantum number
Show Answer
Correct Answer: C [Magnetic quantum number]
Notes:
Magnetic quantum number gives information about the spatial orientation of the orbital with respect to standard set of co-ordinate axis.
42. What do we call the region where the probability density function reduces to zero?
[A] shells
[B] orbits
[C] nodes
[D] None of the above
Show Answer
Correct Answer: C [nodes]
Notes:
The region where the probability density function reduces to zero is called nodal surfaces or simply nodes.
43. Which of the following is correct about effective nuclear charge experienced by the orbital?
[A] it increases with increase of azimuthal quantum number
[B] it increases with increase of magnetic quantum number
[C] it decreases with increase of azimuthal quantum number
[D] It is same everywhere
Show Answer
Correct Answer: C [it decreases with increase of azimuthal quantum number]
Notes:
Because of the screening effect, the net positive charge experienced by the electron from the nucleus is lowered and is known as effective nuclear charge. Effective nuclear charge experienced by the orbital decreases with increase of azimuthal quantum number(l).
44. What will be the number of neutrons in an atom having atomic number 35 and mass number 80?
[A] 35
[B] 45
[C] 55
[D] 80
Show Answer
Correct Answer: B [45]
Notes:
The total number of nucleons is termed as mass number (A) of the atom. In this case, mass number is 80. Therefore, sum of the number of neutrons and protons is 80. As atomic number is 35, we know that number of protons is 35. Hence, number of neutrons = 80-35 = 45.
45. Which of these species are isoelectronic?
[A] Al+ , B–
[B] Mg+ , Cu–
[C] Na+ , Al–
[D] Na+ , F–
Show Answer
Correct Answer: D [Na+ , F–]
Notes:
Isoelectronic species are those species which have the same number of electrons. In the above case, both Na+ and F– have 10 electrons.
46. What is Zeeman effect?
[A] splitting of spectral line in presence of magnetic field
[B] splitting of spectral line in presence of electric field
[C] convergence of spectral line in presence of magnetic field
[D] convergence of spectral line in presence of electric field
Show Answer
Correct Answer: A [splitting of spectral line in presence of magnetic field]
Notes:
Zeeman effect refers to the splitting of a spectrum line into several components by the application of a magnetic field. It is named after the Dutch physicist Pieter Zeeman.
47. What do we call the ratio of number of fission produced by a given generation of neutrons to the number of fission of the preceding generation?
[A] Critical factor
[B] Energy factor
[C] Multiplication factor
[D] Moderation factor
Show Answer
Correct Answer: C [Multiplication factor]
Notes:
The multiplication factor is the ratio of number of fission produced by a given generation of neutrons to the number of fission of the preceding generation.
48. Which of the following is emitted in alpha decay?
[A] Helium nucleus
[B] Hydrogen nucleus
[C] Electrons
[D] Carbon nucleus
Show Answer
Correct Answer: A [Helium nucleus]
Notes:
In alpha decay, Helium nucleus is emitted. Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus transforms or ‘decays’ into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two.
49. Which of the following is an endothermic reaction?
[A] Decomposition of calcium carbonate to calcium oxide and carbon dioxide
[B] Respiration
[C] Burning of Natural gas
[D] All of the above
Show Answer
Correct Answer: A [Decomposition of calcium carbonate to calcium oxide and carbon dioxide]
Notes:
Decomposition of calcium carbonate to calcium oxide and carbon dioxide is an endothermic reaction. Respiration and Burning of Natural gas are examples of exothermic reactions.
50. Which of the following reactions represents changing of green colour of ferrous sulphate?
[A] Double Displacement reaction
[B] Displacement reaction
[C] Combination reaction
[D] Decomposition reaction
Show Answer
Correct Answer: D [Decomposition reaction]
Notes:
A reaction in which a single reactant breaks down to give simpler products is known as decomposition reaction. Ferrous sulphate crystals lose water when heated and the colour of the crystals changes. It then decomposes to ferric oxide, sulphur dioxide and sulphur trioxide.
