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
31. Which of the following molecules have a T-shape arrangement?
[A] Ozone
[B] Water
[C] Chlorine Trifluoride
[D] Sulphur dioxide
Show Answer
Correct Answer: C [Chlorine Trifluoride]
Notes:
Chlorine trifluoride has 10 electrons around the central chlorine atom. There are five electron pairs arranged in a trigonal bipyramidal shape and two equatorial lone pairs making the final structure T-shaped.
32. 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.
33. Choose the correct statement about covalent compounds?
[A] The forces of interaction between them is weak
[B] They are poor conductors of electricity
[C] Both a and b
[D] None of the above
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Correct Answer: C [Both a and b]
Notes:
The covalent compounds have low melting and boiling points due to weak forces of interaction between the molecules. The covalent compounds are poor conductors of electricity as these lack ionic species.
34. Which of the following represents the bond order in Molecular orbital theory?
[A] half the difference between the number of bonding and antibonding electrons
[B] twice the difference between the number of bonding and antibonding electrons
[C] the difference between the number of bonding and antibonding electrons
[D] the sum of the number of bonding and antibonding electrons
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Correct Answer: A [half the difference between the number of bonding and antibonding electrons]
Notes:
The bond order in Molecular orbital theory is given by half the difference between the number of bonding and antibonding electrons.
35. What can we predict about the magnetic nature of a doubly occupied molecule?
[A] It will be paramagnetic
[B] It will be diamagnetic
[C] It will exhibit both paramagnetism and diamagnetism
[D] None of the above
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Correct Answer: B [It will be diamagnetic]
Notes:
The Molecular orbital electronic configuration can be used to predict the magnetic nature of the molecule. If all the MO’s are doubly occupied the substance shows diamagnetic behaviour and if one or more MO’s are singly occupied the substance shows paramagnetic behaviour.
36. Where does the oxidation takes place in a Galvanic cell?
[A] Anode
[B] Cathode
[C] Oxidation does not take place
[D] None of the above
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Correct Answer: A [Anode]
Notes:
In a galvanic cell, the half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution. The other half-cell in which reduction takes place is called cathode and it has a positive potential with respect to the solution.
37. What is the direction of current in a galvanic cell?
[A] same as the direction of electrons
[B] opposite to the direction of electrons
[C] Cant be determined
[D] None of the above
Show Answer
Correct Answer: B [opposite to the direction of electrons]
Notes:
As the switch in the galvanic cell is in the on position, the electrons flow from negative electrode to positive electrode. The direction of current flow is opposite to that of electron flow.
38. The cell constant does not depend on which of the following?
[A] distance between the electrodes
[B] area of cross-section of electrodes
[C] nature of electrolyte
[D] None of the above
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Correct Answer: C [nature of electrolyte]
Notes:
The cell constant depends on the distance between the electrodes and their area of cross-section. It has the dimension of length-1.
39. What is the S.I unit of Molar conductivity?
[A] S m3 mol-2
[B] S m2 mol-2
[C] S m-1 mol2
[D] S m2 mol-1
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Correct Answer: D [S m2 mol-1]
Notes:
If conductivity(κ) of the solution is expressed in S m2 and the concentration(c) is expressed in mol m-3, then the units of Molar conductivity are expressed in S m2 mol-1.
40. Which of the following is not a weak electrolyte?
[A] Acetic acid
[B] Carbonic acid
[C] Potassium Hydroxide
[D] All of the above
Show Answer
Correct Answer: C [Potassium Hydroxide]
Notes:
An electrolyte that does not completely dissociate in aqueous solution is known as weak electrolyte. For example: acetic acid, carbonic acid etc. Potassium Hydroxide is a strong electrolyte.
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