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Q76. The number of core electrons in sodium atom is-
- A1
- B2
- C8
- D10
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Answer: D) 10
Q77. The electronic configuration of an atom is 2, 8, 2. The number of valence electrons in it is-
- A10
- B12
- C8
- D2
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Answer: D) 2
Q78. Which of the following particles has 20 neutrons and 18 electrons?
- A₁₇C1ᶾ⁷
- B₁₈Arᶾ⁸
- C₁₉Kᶾ⁹
- D₁₆Sᶾ⁶
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Answer: B) ₁₈Arᶾ⁸
Q79. The nature of elements can be known by-
- Aby electronic configuration
- Bby atomic number
- Cby atomic mass
- DBy atomic weight
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Answer: A) by electronic configuration
Q80. The electronic configuration of the atom with atomic number 20 is-
- A2, 8, 10
- B2, 6, 8, 4
- C2, 8, 8, 2
- D2, 10, 8
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Answer: C) 2, 8, 8, 2
Q81. Which one of the following is the correct electronic configuration of chlorine?
- A2, 7, 8
- B2, 8, 7
- C2, 8, 8
- D7, 8, 2
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Answer: B) 2, 8, 7
Q82. Which of the following electronic configurations is not possible?
- A1s²
- B1s², 2s²2p⁶2d¹⁰, 3s²
- C1s², 2s² 2pµ
- D1s², 2s²2p⁶, 3s¹
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Answer: B) 1s², 2s²2p⁶2d¹⁰, 3s²
Q83. 1s², 2s²2p⁶ is the electronic configuration of?
- ANa and Ne
- BNe and Na⁺
- CNe and F
- DNa⁺ and F
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Answer: B) Ne and Na⁺
Q84. Which of the following electronic configurations is for metallic elements?
- A2, 8
- B2, 8, 7
- C2, 8, 8
- D2, 8, 8, 2
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Answer: D) 2, 8, 8, 2
Q85. Which of the following electronic configurations occurs for metallic elements?
- A2,8
- B2, 8, 7
- C2, 8, 18
- D2, 8, 18, 2
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Answer: D) 2, 8, 18, 2
Q86. The electronic structure of ₁₃AI²⁷ is-
- A2, 8, 2, 1
- B2, 8, 3
- C2, 8, 1, 2
- D3, 8, 2
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Answer: B) 2, 8, 3
Q87. Which of the following electronic structures is that of sodium ion?
- A2, 8, 1
- B2, 8
- C2, 8, 8
- D2, 8, 7
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Answer: B) 2, 8
Q88. If the number of orbits is expressed by n, then the maximum number of electrons in any orbit will be-
- An
- Bn²
- C2n²
- D2nᶟ
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Answer: C) 2n²
Q89. How many electrons can be present in the outermost orbit of an atom?
- A2
- B8
- C18
- D16
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Answer: B) 8
Q90. If the third orbit of an atom is the outermost orbit, what is the maximum number of electrons it can hold?
- A8
- B16
- C18
- D36
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Answer: C) 18
Q91. The maximum number of electrons that an atom of an element can have in its second orbit is-
- A8
- B32
- C18
- D2
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Answer: A) 8
Q92. Which of the following is the maximum number of electrons that can be present in the M shell?
- A2
- B8
- C18
- D32
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Answer: C) 18
Q93. What is the maximum number of electrons in the N shell?
- A2
- B8
- C18
- D32
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Answer: D) 32
Q94. Atoms are electrically-
- Apositively
- Bnegatively
- Cbipositively
- Dindifferently
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Answer: D) indifferently
Q95. The correct relation between energy (E), momentum (p) and velocity (c) of a photon is-
- Ap=Ec²
- Bp=Ec
- Cp=c/E
- Dp=E/c
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Answer: D) p=E/c
Q96. Stable nuclei (with light A < 10) have-
- Ahave approximately equal numbers of neutrons and protons
- Bhave more neutrons than protons
- Cthere are no neutrons
- DThere are no protons
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Answer: A) have approximately equal numbers of neutrons and protons
Q97. The chemical nature of an element depends on-
- Aon impulse
- Bon the electron
- Con the valence electron
- DOn the proton
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Answer: C) on the valence electron
Q98. The effective radius of an atom is-
- A10¯⁶m
- B10¯¹⁰m
- C10¯¹⁴m
- D10¯¹⁵m
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Answer: B) 10¯¹⁰m
Q99. Which one of the following statements regarding the atomic weight of an element is most appropriate?
- AThe atomic mass of an element is the sum of the protons and neutrons present in the atom of that element.
- BThe atomic weight of an element can vary depending on its mass number.
- CThe atomic weight of an element is an integer
- DAll atoms of an element have the same atomic weight
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Answer: B) The atomic weight of an element can vary depending on its mass number.