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Chemistry Class 9 Chapter 7


Updated: 04 Nov 2023

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Chemistry Class 9 Chapter 7 is about “Electrochemistry”. This article includes the MCQs of Chemistry class 9th chapter 7.

Chemistry Class 9 Chapter 7 Notes

Electrochemistry Notes

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Chemistry Class 9 Chapter 7 Notes

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Chemistry Class 9 Chapter 7 MCQs

1. In electrochemistry, we study about _______ changes.
(a) Physical
(b) Chemical
(c) Analytical
(d) Industrial
Show Answer

Chemical


2. Electrochemistry is the interconversion of electrical energy and ________energy.
(a) Chemical
(b) Potential
(c) Kinetic
(d) Physical
Show Answer

Chemical


3. Electrons are lost in oxidation and gained in reduction, therefore, when oxidation occur in a chemical reaction, reduction must occur__________.
(a) separately
(b) Simultaneously
(c) Formally
(d) All of these
Show Answer

Simultaneously


4. The addition of _____to substance is called oxidation.
(a) Carbon
(b) Hydrogen
(c) Oxygen
(d) Helium
Show Answer

Oxygen


5. C + O_2 \quad \longrightarrow ?
(a) CO_2
(b) CO + O_2
(c) CO_3
(d) None \ of \ these
Show Answer

CO_2

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6. The _________ of hydrogen or other electropositive elements from a substance is called oxidation.
(a) Addition
(b) Removal
(c) change
(d) All of these
Show Answer

Removal


7. 2NH_3 + 3Cl_2 \quad \longrightarrow ?
(a) N_2+3H_2+3Cl_2
(b) 2NH_2+4HCl
(c) N_2¬+6HCl
(d) H_2+ SO_4
Show Answer

N_2+6HCl


8. The removal of ___________from a substance is called oxidation.
(a) Electrons
(b) Proton
(c) Neutrons
(d) None of these
Show Answer

Electrons


9. Fe^{+2} \quad \longrightarrow Fe^{+3} + e^- . What process has occurred?
(a) Aeration
(b) Oxidation
(c) Reduction
(d) Induction
Show Answer

Oxidation


10. The removal of __________from a substance is called reduction.
(a) Carbon
(b) Hydrogen
(c) Oxygen
(d) Nitrogen
Show Answer

Oxygen


11. 2HgO \quad \longrightarrow 2Hg + O_2 is due to
(a) Catalyst
(b) Heating
(c) Reagent
(d) Melting
Show Answer

Heating


12. The addition of ___________to a substance is called reduction.
(a) Hydrogen
(b) Sulpher
(c) Oxygen
(d) Nitrogen
Show Answer

Hydrogen


13. N_2 + 3H_2 \quad \longrightarrow ?
(a) NH_4 + NH_2
(b) 2NH_2 + H_2
(c) 2NH_3
(d) None \ of \ these
Show Answer

2NH_3


14. The _________ of electrons to a substance is called reduction.
(a) Protons
(b) electrons
(c) Neutrons
(d) All of these
Show Answer

electrons


15. Sn^{+4} + 2e^- \quad \longrightarrow Sn^{+2}. What has happened in this chemical reaction?
(a) Gain of election
(b) Loss of electrons
(c) Loss of protons
(d) None of these
Show Answer

Gain of election


16. Those reaction in which gain and loss of electrons takes place simultaneously is called _____ reaction.
(a) Displacement
(b) redox
(c) Cathodic
(d) None of these
Show Answer

redox


17. _________ \quad \longrightarrow 2NaCl
(a) Na + Cl
(b) 2Na + Cl
(c) 2Na + Cl_2
(d) 5Na + Cl_3
Show Answer

2Na + Cl_2


18. The apparent charge, positive or negative, on an atom of an element in a molecular or ion is called _________.
(a) Oxidation number
(b) Oxidation state
(c) Both a and b
(d) None of these
Show Answer

Both a and b


19. Unlike ionic charges, oxidation number do not have an exact ________meaning.
(a) physical
(b) Organic
(c) Biological
(d) Chemical
Show Answer

physical


20. The _________ of solution changes with change of oxidation state.
(a) Structure
(b) colour
(c) Elegance
(d) None of these
Show Answer

colour


21. The oxidation number of all elements in free state is:
(a) Zero
(b) Positive
(c) Negative
(d) Neutral
Show Answer

Zero


22. Which of the following has zero oxidation state?
(a) H_2
(b) Cl_2
(c) Na
(d) All \ of \ these
Show Answer

All of these


23. The oxidation number of __________is the same as the charge on it
(a) Simple ion
(b) Molecular ion
(c) Molecule
(d) Molecular force
Show Answer

Simple ion


24. The oxidation number of hydrogen in its compound is:
(a) +5
(b) +1
(c) +7
(d) +3
Show Answer

+1


25. In the exceptional case of metal hydrides, hydrogen has _____________oxidation state.
(a) -5
(b) -1
(c) -7
(d) -3
Show Answer

-1


26. The oxidation number of oxygen in its compound is:
(a) -2
(b) -3
(c) -4
(d) -5
Show Answer

-2


27. In case of peroxide, oxygen has _____________ oxidation state.
(a) -4
(b) -3
(c) -2
(d) -1
Show Answer

-1


28. The oxidation number of each element of group 1 is.
(a) +1
(b) +2
(c) +3
(d) +4
Show Answer

+1


29. The oxidation state of each element of group 2 is.
(a) +1
(b) +2
(c) +3
(d) +4
Show Answer

+2


30. The oxidation state of each element of group 3 is :
(a) +1
(b) +2
(c) +3
(d) +4
Show Answer

+1


31. The oxidation number of each element of halogens in their binary compound is ______________.
(a) +1
(b) -1
(c) +3
(d) -3
Show Answer

-1


32. In neutral molecules, the algebraic sum of the oxidation number of all the elements is _______________.
(a) Zero
(b) Five
(c) Seven
(d) Nine
Show Answer

Zero


33. In any substance, the more __________ action has the negative oxidation number.
(a) Electropositive
(b) Neutral
(c) electronegative
(d) None of these
Show Answer

electronegative


34. An oxidizing agent is a specie that ____________a substance and itself get reduce.
(a) oxidizes
(b) Neutralize
(c) Reduce
(d) None of these
Show Answer

oxidizes


35. What is the example of oxidizing agent?
(a) KMnO_4
(b) H_2S
(c) Na
(d) Al
Show Answer

KMnO_4


36. An oxidizing agent may be the ________ of oxygen to a substance.
(a) Acceptor
(b) Share
(c) donor
(d) None of these
Show Answer

donor


37. An oxidizing agent may be the __________of a hydrogen from a substance.
(a) Acceptor
(b) Share
(c) Donor
(d) None of these
Show Answer

Acceptor


38. An oxidizing agent may be the acceptor of _____from a substance.
(a) Proton
(b) electron
(c) Neutron
(d) None of these
Show Answer

electron


39. The oxidation number of an oxidizing agent is ________during a redox reaction.
(a) decreased
(b) Constant
(c) Increased
(d) None of these
Show Answer

decreased


40 A specie that reduces a substance and itself gets oxidized is called ____________agent.
(a) Oxidizing
(b) Reducing
(c) Reducing sugars
(d) All of these
Show Answer

Reducing


41. Which of the following is a reducing agent?
(a) K_2Cr_2O_7
(b) HNO_3
(c) SO_2
(d) Cl_2
Show Answer

SO_2


42. A reducing agent may be the acceptor of ________from a substance.
(a) oxygen
(b) Hydrogen
(c) Carbon
(d) Helium
Show Answer

oxygen


43. A reducing agent may be the ______________of hydrogen to a substance.
(a) Acceptor
(b) Share
(c) Donor
(d) None of these
Show Answer

Donor


44. A reducing agent may be the donor of an ______to a substance.
(a) Proton
(b) Electron
(c) Neutron
(d) All of these
Show Answer

Electron


45. The oxidation state of a reducing agent is ________during a redox reaction.
(a) Increased
(b) Constant
(c) Decreased
(d) None of these
Show Answer

Increased


46. Cu^{+2} + Zn^o \quad \longrightarrow Zn^{+2} + Cu^? What will be the oxidation state of copper in products?
(a) 0
(b) +1
(c) -1
(d) +2
Show Answer

0


47. A device in which inter conversion of electrical and chemical energies takes place is called __________.
(a) Battery
(b) Electrode
(c) Electrochemical Cell
(d) None of these
Show Answer

Electrochemical Cell


48. An _________ is a substance in solution or in molten state, which ionizes into positive and negative ions and conducts electricity.
(a) Electrolyte
(b) Battery
(c) Isomer
(d) None of these
Show Answer

Electrolyte


49. Which of the following is the example of electrolyte?
(a) NaCl
(b) HCl
(c) NaOH
(d) All \ of \ them
Show Answer

All of them


50. Those substances which ionize completely in aqueous solution or in molten state and conduct electric current to a larger extent is called _____________.
(a) Weak electrolyte
(b) Strong electrolyte
(c) Non-electrolyte
(d) None of these
Show Answer

Strong electrolyte


51. Which of the following is the example of strong electrolyte?
(a) H_2SO_4
(b) NH_4OH
(c) C_6H_6
(d) None \ of \ these
Show Answer

H_2SO_4


52. Those substances which ionizes partially in aqueous solution or in molten state and conduct electricity to a very small extent is called_____________.
(a) Strong electrolyte
(b) Weak electrolyte
(c) Non-electrolyte
(d) None of these
Show Answer

Weak electrolyte


53. Which of the following is the example of weak electrolyte?
(a) Urea
(b) NaCl
(c) CH_3COOH
(d) None \ of \ these
Show Answer

CH_3COOH


54. CH_3COOH_{(aq)} \quad \longrightarrow ?
(a) CH_3COO^-_{(aq)} + H^+_{(aq)}
(b) C_2O_2^- + 2 H_2^+
(c) CH_4CO^- + O^+
(d) None \ of \ these
Show Answer

CH_3COO^-_(aq) + H^+_(aq)


55. Those substances which do not dissociate in aqueous solution or in molten state, therefore donot conduct electricity is called_________________.
(a) Strong electrolyte
(b) Weak electrolyte
(c) Non-electrolyte
(d) All of these
Show Answer

Non-electrolyte


56. Which of the following is the example of non-electrolyte?
(a) Sugar
(b) Urea
(c) Glucose
(d) All of these
Show Answer

All of these


57. __________are the conductors i.e. metallic plates, wires or rods, through which electrons enters or leaves the electrolytes in a cell.
(a) Electrodes
(b) Allotropes
(c) Alloys
(d) None of these
Show Answer

Electrodes


58. How many types of electrodes are there?
(a) 1
(b) 2
(c) 3
(d) 4
Show Answer

2


59. The ____________is the positive electrode at which the anion gather and leaves the electron in the electrolytic cell.
(a) Anode
(b) Electrode
(c) Cathode
(d) None of these
Show Answer

Anode


60 What type of charge is there on anions?
(a) Positive
(b) Neutral
(c) Negative
(d) None of these
Show Answer

Negative


61 The __________ is the negative electrode at which cation gathers and gains the electrons in the electrolytic cell.
(a) Anode
(b) Cathode
(c) Electrode
(d) None of these
Show Answer

Cathode


62. What type of charge is there on cations?
(a) Positive
(b) Neutral
(c) Negative
(d) None of these
Show Answer

Positive


63. When electrical energy is required to produce a redox reaction and bring a chemical change in an electrochemical cell is called ____________cell.
(a) Voltaic
(b) Electrolytic
(c) Daniel
(d) None of these
Show Answer

Electrolytic


64. The example of electrolytic cell is ________________.
(a) Down cell
(b) Nelson cell
(c) Daniel cell
(d) Both a and b
Show Answer

Both a and b


65. The process of chemical breakdown of an electrolyte in molten or solution form by passing current is called________.
(a) Electrolysis
(b) Catalysis
(c) Chemolysis
(d) analysis
Show Answer

Electrolysis


66. The electrodes are connected to the terminals of the ___________.
(a) Cell
(b) battery
(c) Both a and b
(d) None the these
Show Answer

battery


67. Pure copper is a good __________of electricity and is used in electrical instruments.
(a) Conductor
(b) Insulator
(c) Non-electrolyte
(d) None of these
Show Answer

Conductor


68. Cupper is purified by _________________.
(a) Destructive distillation
(b) electro-refining
(c) Metallurgy
(d) None of these
Show Answer

electro-refining


69. In electro-refining, cupper is purified by applying _______ temperature and applied voltage of about 0.3 \ volts .
(a) 50^oC
(b) 25^oC
(c) 100^oC
(d) 75^oC
Show Answer

50^oC


70. In electro-refining of copper, which reaction occurs at anode?
(a) Reduction
(b) Oxidation
(c) Both (a) and (b)
(d) None of these
Show Answer

Oxidation


71. In electro-refining of copper, reduction occurs at ____________.
(a) cathode
(b) Anode
(c) Both and b
(d) None of these
Show Answer

cathode


72. By electrolytic refining, upto _____________pure copper is obtained.
(a) 90.3%
(b) 93.5%
(c) 95.9%
(d) 99.9%
Show Answer

99.9%


73. The device in which chemical energy is converted into electrical energy is called ___________cell.
(a) Electrolytic
(b) Voltaic
(c) Galvanic
(d) Both a and b
Show Answer

Both a and b


74. In voltaic cell, which type of reaction occurs?
(a) spontaneous
(b) Non-spontaneous
(c) Both (a) and (b)
(d) None of these
Show Answer

spontaneous


75. The example of voltaic cell is _____________cell.
(a) Down
(b) Daniel
(c) Nelson
(d) All of these
Show Answer

Daniel


76. A galvanic cell consists of two separate containers, each container is called a _____________.
(a) Half cell
(b) Binary cell
(c) Electrode
(d) None of these
Show Answer

Half cell


77. In each half cell, an electrode is dipped in 1M solution of its own____________.
(a) Acid
(b) Base
(c) Salt
(d) All of them
Show Answer

Salt


78. The two solutions in different containers are connected with bridge called ___________.
(a) Salt bridge
(b) Smudge
(c) Sludge
(d) Clutch
Show Answer

Salt bridge


79. The salt bridge is a _____________tube.
(a) C-shaped
(b) O-shaped
(c) U-shaped
(d) L-shaped
Show Answer

U-shaped


80. The U-Shaped tube in voltaic cell is filled with ________________.
(a) Electrolyte gel
(b) Suspension
(c) Allotropes
(d) None of these
Show Answer

Electrolyte gel


81. The example of electrolytic gel present in the bridge of voltaic cell is _________________.
(a) NaCl
(b) K_2SO_4
(c) H_2SO_4
(d) Cl^-
Show Answer

K_2SO_4


82. The net chemical changes obtained by adding the __________half cell reactions are called cell reaction.
(a) 02
(b) 04
(c) 06
(d) 08
Show Answer

02


83. A Galvanic cell converts chemical energy into _________energy.
(a) Biological
(b) Kinetic
(c) Potential
(d) electrical
Show Answer

electrical


84. An electrolytic cell converts electrical energy into _________energy.
(a) Kinetic
(b) Chemical
(c) Potential
(d) Heat
Show Answer

Chemical


85. In Galvanic cell, the redox reaction is _____________.
(a) Spontaneous
(b) Constant
(c) Non-spontaneous
(d) None of these
Show Answer

Spontaneous


86. In electrolytic cell, the redox reaction is _______________.
(a) spontaneous
(b) Constant
(c) Non-spontaneous
(d) None of these
Show Answer

Non-spontaneous


87. A group of _______cells joined in series is called battery.
(a) Electrolytic
(b) galvanic
(c) Nelson
(d) None of these
Show Answer

galvanic


88. Car batteries consist of __________or more identical voltaic cells connected in series.
(a) 6
(b) 9
(c) 12
(d) 15
Show Answer

6


89. A battery converts chemical energy into __________energy.
(a) Potential
(b) Kinetic
(c) Electrical
(d) Chemical
Show Answer

Electrical


90. The dry cell was prepared by LECLANCHE in ________________.
(a) 1787
(b) 1887
(c) 1987
(d) 1947
Show Answer

1887


91. The electrochemical cell or batteries are used in _____________.
(a) Flashlights
(b) Calculators
(c) Automobiles
(d) All of them
Show Answer

All of them


92. Sodium was first discovered by an English chemist ____________in 1807.
(a) Humphrey Davey
(b) Leclanche
(c) Gregory
(d) None of these
Show Answer

Humphrey Davey


93. The melting point of sodium chloride is ____________.
(a) 801^oC
(b) 1000^oC
(c) 1890^oC
(d) 1313^oC
Show Answer

801^oC


94. Which of the following is the most abundant metal on earth’s crust?
(a) Zinc
(b) Gold
(c) Mercury
(d) Aluminum
Show Answer

Aluminum


95. A concentrated aqueous solution of sodium chloride (NaCl) is called_________.
(a) Asbestos
(b) brine
(c) Catalyst
(d) Dry cell
Show Answer

brine


96. A slow and continuous eating away of a metal by the environment is called____________.
(a) Rust
(b) corrosion
(c) Radical
(d) Isotope
Show Answer

corrosion


97. Corrosion is a naturally occurring spontaneous phenomena and it drives materials to its _______possible energy states.
(a) Lowest
(b) Intermediate
(c) Highest
(d) None of these
Show Answer

Lowest


98. Corrosion is oxidation-reduction process which takes place by the action of _________in presence of moisture with the metals.
(a) NH_3
(b) Air
(c) Sulpher
(d) hydrogem
Show Answer

Air


99. The most common example of corrosion is rusting of :
(a) Gold
(b) Silver
(c) iron
(d) Platinium
Show Answer

iron


100. The corrosion of iron is commonly known as___________.
(a) Rusting
(b) Corrosion
(c) Detoxification
(d) Purification
Show Answer

Rusting


101. The necessary conditions for rusting is __________.
(a) Moisture
(b) Air
(c) CO_2
(d) Both (a) and (b)
Show Answer

Both (a) and (b)


102. Iron rusts by combining with oxygen in the presence of :
(a) Chloroform
(b) Water
(c) Benzene
(d) Ester
Show Answer

Water


103. When iron rusts, it forms brown hydrated mass called ______________.
(a) Ferric oxide
(b) Ferrous oxide
(c) Ferrum oxide
(d) None of these
Show Answer

Ferric oxide


104. Dents and stains are the site for the process of ______________.
(a) Evaporation
(b) Condensation
(c) rusting
(d) None of these
Show Answer

rusting


105. At anode, 2Fe_{(s)} \quad \longrightarrow 2Fe^{+2}_{(aq)} + _______________.
(a) 2es^-
(b) 4es^-
(c) 6es^-
(d) 8es^-
Show Answer

4es^-


106. The loss of electron _________the metal.
(a) damage
(b) Stable
(c) Repair
(d) None of these
Show Answer

damage


107. The rust mass is _______ and porous in nature and therefore cannot prevent further atmospheric action.
(a) Hard
(b) Allergic
(c) Soft
(d) None of these
Show Answer

Soft


108. Paints and coatings are used to _________metal from corrosion effects.
(a) protect
(b) Damage
(c) Corrode
(d) None of these
Show Answer

protect


109. The modern paints contain a combination of chemicals called____________.
(a) Suspension
(b) Isomers
(c) stabilizers
(d) None of these
Show Answer

stabilizers


110. An __________is a homogenous mixture of metals or a mixture of metals and non-metals.
(a) Isotope
(b) Alloy
(c) Polonium
Show Answer

Alloy



(d) None of these 111. Alloying also helps to ________corrosion of metals.
(a) Protect
(b) Damage
(c) Corrode
(d) All of these
Show Answer

Protect


112. The best example of alloy is a __________which is a solid mixture of iron, chromium and nickel.
(a) PVC
(b) Acetylene
(c) Stainless steal
(d) None of these
Show Answer

Stainless steal


113. A thin coating of one metal on another can applied by ___________.
(a) Spraying
(b) Galvanizing
(c) Electroplating
(d) All of them
Show Answer

All of them


114. ___________protection is used to protect iron in buried fuel tanks and pipelines.
(a) Alloying
(b) Cathodic
(c) Paints
(d) Plating
Show Answer

Cathodic


115. When metal ion is reduced by passing electricity and a solid metal is deposited on a surface is called ______.
(a) electroplating
(b) Galvanizing
(c) Half Cell
(d) None of these
Show Answer

electroplating


116. The __________is an aqueous solution of a salt of the respective metal which is to be deposited on the metal.
(a) electrolyte
(b) Bas
(c) Acid
(d) None of these
Show Answer

electrolyte


117. An electroplating is used to weld the broken parts of the machinery by depositing the ______on it.
(a) Non-metal
(b) Gas
(c) Metal
(d) None of these
Show Answer

Metal


118. An electroplating is used for _____purposes.
(a) Corrosion
(b) decoration
(c) Ionization potential
(d) None of these
Show Answer

decoration


119. To deposit the noble metals like ___________and silver on an inferior metal to enhance its beauty.
(a) Gold
(b) Lithium
(c) Rhodium
(d) None of these
Show Answer

Gold


120. The oxidation number nitrogen N_2 is
(a) +1
(b) +3
(c) 0
(d) -3
Show Answer

0


121. What is the oxidation number C \ in \ CH_3OH:
(a) -2
(b) -1
(c) 0
(d) +1
Show Answer

-2


122. A cation is:
(a) Neutral
(b) Negatively charged
(c) Positively charged
(d) No charges
Show Answer

Positively charged


123. Electrons are lost by the :
(a) Reducing agent as it undergoes oxidation
(b) Reducing agent as it undergoes reduction
(c) Oxidizing agent as it undergoes oxidation
(d) Oxidizing agent as it undergoes reduction
Show Answer

Reducing agent as it undergoes oxidation


124. What is the oxidation number assigned to manganese in KMnO¬4:
(a) +7
(b) +3
(c) +2
(d) +4
Show Answer

+7


125. In a particular redox reaction, the oxidation number of phosphorus changed from -3 to 0. From this information, it may be concluded that phosphorus:
(a) Last 3 electrons and was reduced
(b) Last 3 electrons and was oxidized
(c) Gained 3 electrons and was reduced.
(d) Gained 3 electrons and was oxidized.
Show Answer

Last 3 electrons and was reduced


126. Which statement is true for an electrochemical cell;
(a) Oxidation occurs at the anode only
(b) Reduction occurs at the anode only
(c) Oxidation occurs at both the anode and cathode
(d) Reduction occurs at both the anode and cathode.
Show Answer

Oxidation occurs at the anode only


127. In which of the following does Sulpher have an oxidation number of +7:
(a) HSO-3
(b) SO3
(c) H2SO4
(d) H¬2S2O8 128. What happens to the reducing agent in an oxidation-reduction reaction:
(a) It is oxidized as it gains electrons
(b) It is oxidized as it loses electrons
(c) It is reduced as it gains electrons
(d) It is reduced as it loses electrons.
Show Answer

It is oxidized as it loses electrons


129. In an electrochemical cell, electrons travel in which direction
(a) From the anode to the cathode through the external circuit
(b) From the anode to the cathode through the salt bridge.
(c) From the cathode to the anode through the external circuit
(d) From the cathode to the anode through the salt bridge
Show Answer

From the anode to the cathode through the external circuit

Chemistry Class 9 MCQs (All Chapters)


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