Chemistry Chapter 9 Entry Test MCQs
Topic 9
Basic Concepts
1. The oxidation state of oxygen in O2 is
a. + ½
b. Zero
c. + 1
d. – ½
2. A number which is assigned to each atom or ion in a compound which explains its degree of oxidation is called
a. oxidation number
b. oxidation state only
c. oxidation state and number
d. oxidation degree only
3. The oxidation number of carbon in CH2Cl2 is
a. 3
b. 0
c. 5
d. 2
4. What is the oxidation number of iron in the compound [Fe(H2O)5(NO+)]2+?
a. + 3
b. + 5
c. + 1
d. + 2
5. The electric conduction of a salt solution in water depends on the
a. Size of its molecules
b. Shape of its molecules
c. Extent of its ionization
d. Size of solvent molecules
6. The amount of ion discharged during electrolysis is not directly proportional to:
a. Current
b. Resistance
c. Chemical equivalent of ion
d. Time
7. When a solution of an electrolyte is heated the conductance of the solution:
a. Decreases because of the dissociation of the electrolyte is suppressed
b. Increases because of the electrolyte conducts better
c. Increases because the electrolyte is dissociated more
d. Decreases because of the increased heat
8. Pure water does not conduct electricity because it:
a. Is almost totally unionized
b. Has a low boiling point
c. Is readily decomposed
d. Is neutral
9. In which of the following changes there is a transfer of five electrons
a. CrO4 –2 → Cr+3
b. MnO42- → MnO2
c. Cr2O7 2– → 2Cr+3
d. MnO4 – → Mn+2
10. The oxidation number of sulphur in Na2S4O6 is:
a. + 2.5
b. + 2
c. + 6
d. + 4
11. In which of the following compounds, oxidation number of sulphur is negative:
a. H2S
b. SO2
c. Na2SO4
d. H2SO4
12. Which of the following has same oxidation state in all of its compounds?
a. Cl
b. Be
c. N
d. Br
13. When heating one end of a metal plate, the other end gets hot because of
a. mobility of atoms in the metal
b. the resistance of the metal
c. minor perturbation in the energy of atoms.
d. energised electrons moving to the other end
14. Electrochemistry is the branch of physical chemistry that deals with the study of….
a. chemical change
b. physical change
c. chemical and electrical change
d. mechanical change
15. Some statements are given below…. among the below incorrect is/are
- oxidation involve loss of electron
- during Oxidation, Oxidation number decreases.
a. only 2
b. 1 and 3
c. 1, 2 and 4
d. 2 and 4
16. A device used to study chemical reactions electrically is known as….
a. electro chemical cell
b. electrolytic cell
c. dry cell
d. Fuel cell
17. Which one of the following does not conduct electricity?
a. NaCl crystal
b. Molten NaCl
c. conc. solution of NaCl in water
d. dil. solution of NaCl in water
18. The oxidation state of oxygen in oxides, peroxides and super oxides is
a. -2, – 1, – ½
b. -2, +2, – 1
c. -2, – 1/2, – 1
d. -1, – 2, +1
19. To balance oxygen in ion electron method in acidic medium, we add
a. H2O
b. H+ ion
c. O2
d. OH– ion
20. HBr is formed when bromine reacts with molecular hydrogen at high temperature. H2 + Br2 → 2HBr, the reaction is an example of
a. Oxidation
b. Disproportionation
c. Redox
d. Reduction
21. Consider the following reaction 2Cr2O72- aq + 16H+aq + 3C2H5OH aq –––→ 4Cr3+ aq + 11 H2O(I)+ 3CH3COOH(aq) Atom undergoes decrease in oxidation number is:
a. Hydrogen
b. Carbon
c. Chromium
d. Oxygen
22. The charge required for the reduction of 1 mol of MnO2 to MnO2– is
a. 5
b. 1
c. 6
d. 3
23. Formation of ZnSO4 from blue copper sulphate solution is a spontaneous
a. Reduction Reaction
b. Oxidation reaction
c. Redox reaction
d. Addition Reaction
24. Which reaction is an example of redox reaction
a. H+ + O-H → H2O
b. CuO + H2SO4→ CuSO4 + H2O
c. 2SO2+O2→2SO3
d. Ag+ +Cl– → AgCl
25. The correct order of compounds with increasing oxidation number of phosphorus is
a. P2O3 < P4 < PH3
b. P4 < PH3 < P2O3
c. PH3 < P4 < P2O3
d. P4 < P2O3 < PH3