General Science Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination
61. Which of the following quantum numbers is represented by a period of the modern periodic table?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] None of the above
Show Answer
Correct Answer: A [Principal quantum number]
Notes:
The Period in the modern periodic table indicates the value of ‘n’ (principal quantum number) for the outermost or valence shell.
62. Which of these elements do not belong to the same group?
[A] Nickel
[B] Platinum
[C] Darmstadtium
[D] Roentgenium
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Correct Answer: D [Roentgenium]
Notes:
Nickel, Platinum and Darmstadtium belongs to Group number 10 whereas element Roentgenium is placed in group number 11.
63. What is the molecular geometry of HgCl2?
[A] Linear
[B] Trigonal Planar
[C] Tetrahedral
[D] Octahedral
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Correct Answer: A [Linear]
Notes:
The molecular geometry of Mercuric chloride (HgCl2) is Linear. As there is no lone pairs with Hg and the number of bonding pairs. Therefore, the hybridization is SP hybridization and the structure is Linear.
64. What do the dots represent in the Lewis dot structures?
[A] positrons
[B] electrons
[C] atoms
[D] neutrons
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Correct Answer: B [electrons]
Notes:
The dots in the Lewis dot structure represent electrons. Lewis introduced theses simple notations to represent valence electrons in an atom.
65. What is the bond formed due to the electrostatic attraction known as?
[A] Covalent bond
[B] Electrovalent bond
[C] Electromagnetic bond
[D] Polar bond
Show Answer
Correct Answer: B [Electrovalent bond]
Notes:
The bond formed, as a result of the electrostatic attraction between the positive and negative ions is termed as Electrovalent bond. It is also known as Ionic bond.
66. Choose the correct statement:
[A] When acids and bases react, salt is formed
[B] Reaction between an acid and a base is known as a neutralisation reaction
[C] Both a and b
[D] None
Show Answer
Correct Answer: C [Both a and b]
Notes:
The chemical reaction between an acid and a base to give a salt and water is known as a neutralisation reaction.
67. What can be the probable pH of Milk of Magnesia?
[A] 2
[B] 5.5
[C] 7
[D] 10.5
Show Answer
Correct Answer: D [10.5]
Notes:
Milk of Magnesia is the common name of Magnesium Hydroxide. It is an alkaline base and has an overall pH of around 10.5.
68. Choose the incorrect acid-source pair?
[A] Citric acid – Lemon
[B] Lactic acid – Sour milk
[C] Oxalic acid – Ant sting
[D] Methanoic acid – Nettle sting
Show Answer
Correct Answer: C [Oxalic acid – Ant sting]
Notes:
An ant sting contains Methanoic acid. The sting leaves an acid which causes irritation. Use of a mild base like baking soda on the stung area gives relief.
69. What is the chemical name of Bleaching powder?
[A] Calcium Oxychloride
[B] Calcium Monosulphate
[C] Calcium Tetrachloride
[D] Sodium chloride
Show Answer
Correct Answer: A [Calcium Oxychloride]
Notes:
Calcium Oxychloride or CaOCl2 is the chemical name of Bleaching powder. It is a very important industrial chemical having its use in paper, textile and other areas.
70. Choose the correct about Phenolphthalein as an indicator?
[A] It turns red in acids and yellow in bases
[B] It turns colourless in acids and pink in bases
[C] It turns orange in acids and brown in bases
[D] It turns colourless in acids and green in bases
Show Answer
Correct Answer: B [It turns colourless in acids and pink in bases]
Notes:
Phenolphthalein is a weak acid that is commonly used as an indicator. It is colourless in acids and pink in bases.
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