1. The process in which oxidation number increases is
(1) Reduction
(2) Hydrolysis
(3) Oxidation
(4) Decomposition
Sol. Answer (3)
Oxidation number increases in oxidation reaction.
2. The oxidation number of phosphorus vary from
(1) – 3 to + 5
(2) – 1 to + 1
(3) – 3 to + 3
(4) – 5 to + 1
Sol. Answer (1) Phosphorus has 5 valence
electrons. Hence, its oxidation number varies from –3 to +5
3. Oxidation number of iodine varies from
(1) – 1 to + 1
(2) – 1 to + 7
(3) + 3 to + 5
(4) – 1 to + 5
Sol. Answer (2)
Iodine has 7 valence electrons.
\ Its oxidation number varies from –1 to +7
4. White P reacts with caustic soda, the products are PH3 and NaH2PO2. The reaction is an example of
(1) Oxidation
(2) Reduction
(3) Disproportionation
(4) Neutralization
Sol. Answer (3)
0
-3 +1
P4 + NaOH ¾¾® PH3 + NaH2 PO2
Phosphorus' oxidation state changes from 0 to –3 as
well as +1 i.e. it undergoes disproportionation.
5. Oxidation number of oxygen atom in O3 molecule is
(1) 0
(2) –2
(3) + 2
(4) – ½
Sol. Answer (1)
In O3 (Ozone), there is no electronegativity
difference between two oxygen atoms.
\ Oxidation number is 0.
6. The oxidation number of
C in CH4, CH3Cl, CH2Cl2, CHCl3 and CCl4 is respectively
(1) –4, –2, 0, +2, +4
(2) +2, 4, 0, –2, –4
(3) 4, 2, 0, –2, 4
(4) 0, 2, –2, 4, 4
Sol. Answer (1)
CH4 ¾¾® x + 4 = 0 ⇒ x = -4
CH3Cl ¾¾® x + 3 - 1 = 0 ⇒ x = -2
CH2Cl2 ¾¾® x + 2 - 2 = 0 ⇒ x = 0
CHCl3 ¾¾® x + 1- 3 = 0 ⇒ x = + 2
CCl4 ¾¾® x - 4 = 0 ⇒ x = + 4
7.
Chlorine is in +3 oxidation
number in
(1) HCl
(2) HClO4
(3)
ICl
(4) ClF3
Sol. Answer (4)
8. Given that the oxidation number of sulphur is –2, the equivalent weight of sulphur is
(1) 16
(2) 32
(3) 9
(4) 4
Sol. Answer (1
9. In
a reaction between zinc and iodine, zinc iodide is formed. Which is being oxidised?
(1) Zinc ions
(2) Iodide ions
(3) Zinc atom
(4)
Iodine
Answer (3)
10. In the following equation
2Br2 + 6CO3 2– + 3H2O ®5Br – +BrO₃⁻ + 6HCO₃¯
(1) Bromine is oxidised and carbonate is reduced
(2) Bromine is reduced and carbonate is oxidised
(3) Bromine is neither reduced nor oxidised
(4) Bromine is reduced as well oxidised
11. In which reaction, there is change in oxidation number of N atom?
(1) 2NO2 ¾®
N2O4
(2) 2NO2 + H2O ¾® HNO3 + HNO2
(3) NH4OH ¾® NH4+ + OH–
(4) N2O5 + H2 O ¾® 2HNO3
12. When iron is added to CuSO4 solution, copper is precipitated. It is due to
(1) Oxidation of Cu+2
(2) Reduction of Cu+2
(3) Hydrolysis of CuSO4
(4) Ionization of CuSO4
Answer (2)
13. Which of the following reactions involves oxidation and reduction?
1) NaBr + HCl ¾® NaCl + HBr
2 HBr + AgNO3 ¾® AgBr + HNO3
3) H2 + Br2 ¾® 2HBr
4) Na2O + H2SO4 ¾® Na2SO4 + H2O
Answer (3)
14. Which of the following involves the reduction of copper?
1. Cu(s) + ½ O2(g) ¾® CuO(s)
2. Cu2+(aq) + 2I–(aq) ¾® 2CuI(aq)
3. CuCl2(s) + 2F–(aq) ¾® CuF2 + Cl2(g)
4. CuO + H2O ¾® Cu(OH)2
Answer (2)
15. Which one of the following is the correct match?
1) Cl2 only reducing agent
2) HNO2 only oxidising agent
3) HNO3 both oxidising and reducing agent
4) SO2 both oxidising and reducing agent
Sol. Answer
(4)
Oxidation state of S in SO2 is
+4 So if can undergo oxidation to +6. or undergo reduction to
–2.
16.
The oxidation number of sulphur in H2S2O8 is
(1) + 7
(2) + 6
(3) – 6
(4) + 4
Answer (2)
18. In which of
the following compounds, the oxidation number of iodine is
fractional?
(1) IF₇
(2) I3 –
(3) IF5
(4) IF3
Answer (2
19. Oxidation number of sodium in sodium-amalgam is
(1) +1
(2) 0
(3) –1
(4) +2
Sol. Answer (2)
An amalgam is a homogeneous mixture (Na-Hg)
\ Oxidation state of sodium and mercury in sodium
amalgam is 0.
20. Which the following is not correct for electrochemical cell?
(1) Convert chemical energy to electrical energy
(2)
Anode is –ve terminal
(3) Cathode is –ve terminal
(4)
Cathode is +ve terminal
Sol. Answer (3)
ln an electrochemical cell, cathode is the positive
terminal, not negative.
21. Which of the following is not a redox reaction?
(1) H2 + Cl2 ¾® 2 HCl
(2) NaOH +
HCl ¾® NaCl + H2O
(3) Photosynthesis
(4) Cell respiration
Sol. Answer
(2)
Neutralization
reactions are not redox reactions
NaaOH + HCl ¾¾® NaCl + H2O This is a neutralization reaction.
22. Redox reaction have no concern wit
(1) Neutralization
of acid bases
(2) Salt hydrolysis
(3) Esterification
(4) All of these
Sol. Answer (4)
Redox
reactions have nothing to do with neutralization reactions, salt hydrolysis or esterification reactions since there
is no change in oxidation number.
23. KCl is used as an electrolyte in salt bridge because
(1) K+ and
Cl– are
isoelectronic
(2) Monovalent ions are required
(3) Both the ions have almost same velocity
(4) They
are having similar size
Sol.
Answer (3)
KCl is used in salt bridge since K+ and
Cl– have almost the same ionic velocity.
24. EMF of the given cell
A | A2+ || B2+ | B
Given E° A/A2+= +1.4 V and E°B/B2+ = -1.4 V
(1).
2.8V
(2).
1.8V
(3).
0 V
(1).
-1.8V
Answer (1)
25. Electrode potential depends upon
(1) Size of electrode
(2) Surface area of electrode
(3) Temperature
(4) Shape of electrode
Answer (3)
26. Three metals A, B and C are arranged in increasing order of standard reduction electrode potential( increasing order of standard reduction potential A < B
< C), hence their chemical reactivity order will be
(1) A < B < C
(2) A > B > C
(3) B > C > A
(4) A = B = C
Sol. Answer
(2)
Increasing order of standard reduction
potential A < B < C
\ Increasing order of standard oxidation potential
A > B > C
Metals have tendency to get oxidized
\ Higher the tendency to get oxidized, higher the reactivity
\ Reactivity order:
A > B >
C
27. Which compound acts as oxidising agent only?
(1) SO2
(2) H2S
(3) H2SO4
(4) HNO2
Sol. Answer (3)
In H2SO4 , Sulphur is in
its highest possible oxidation state. Hence it can only undergo reduction and
oxidize others.
28. Find the incorrect statement
(1) Higher reduction potential of non-metal means stronger
reducing agent
(2) Lower oxidation potential of a metal means strong oxidising agent
(3) Oxidation state of oxygen in O3 is –1
(4) All of these
Sol. Answer (4)
Higher reduction potential means higher tendency to
get reduced i.e. better oxidizing agent. Lower oxidation
potential means higher reduction potential means
Þ High tendency to get reduced
Þ High tendency to oxidize others Oxidation state of oxygen in O is 0.
29. The average oxidation state of chlorine in bleaching powder is
(1) –1
(2) +1
(3) Zero
(4) –2 as well as +2
Answer (3)
30. Which of the following is incorrect regarding salt bridge solution?
(1) Solution must be a strong electrolyte
(2) Solution should be inert towards both electrodes
(3) Size of cations and anions of salt should be much different
(4) Salt bridge solution is prepared in gelatin or agar-agar to make it semi-solid
Sol. Answer (3)
In salt bridge, size of cations and anions should
not be much different, they should be similar.
31. (a) H2O2+O3 ® H2O + 2O2
(b) H2O2 + Ag2O ® 2Ag + H2O + O
Role of hydrogen peroxide in the above reactions is respectively.
[AIPMT-2014]
(1) Oxidizing in (a) and reducing in (b)
(2) Reducing in (a) and oxidizing in (b)
(3) Reducing in
(a) and (b)
(4) Oxidizing in (a) and (b)
Answer (3)
32. In which of the following compounds, nitrogen exhibits highest oxidation state? [AIPMT (Prelims)-2012]
(1) N3H
(2) NH2OH
(3) N2H4
(4) NH3
Sol. Answer (1)
33. Standard reduction electrode potential of three metals X, Y and Z are –1.2 V, +0.5 V and –3.0 V respectively.
The reducing power
of these metals will be
(1) X > Y > Z
(2) Y > Z > X
(3) Y > X > Z
(4) Z > X > Y
Sol. Answer (4)
Higher reduction potential Þ stronger oxidizing power Þ Weaker reducing power
\ Reducing power : Y < X < Z
34. In the reaction 2H2O2 ® 2H2O + O2
(1) Oxygen is oxidised only
(2) Oxygen is
reduced only
(3) Oxygen is neither oxidised nor reduced
(4) Oxygen is
both oxidised and reduced
Answer (4)
35. Given the following reactions involving A, B, C and D
(i) C + B+ ® C+ + B
(ii) A+ + D ® No reaction
(iii) C+ + A ® No reaction
(iv) D + B+ ® D+ + B
The correct arrangement of A, B, C, D in order of
their decreasing ability as reducing agent
(1) D > B > C > A
(2) A > C > D > B
(3) C > A > B > D
(4) C > A > D > B
Sol. Answer
(4)
From the data, it is concluded that D cannot reduce A+
A cannot reduce C+
Þ Reducing power ¾¾® C > A > D
Also, It is
seen that D reduces B+
\ Reducing power ¾¾® C > A > D > B
36. Which element undergoes disproportionation in water?
(1) Cl2
(2) F2
(3) K
(4) Cs
Sol. Answer
(1)
Cl in water
disproportionate to give HCl and HOCl
Cl2 + H2O ¾¾® HCl + HOCl
37. Standard reduction potentials at 25°C of Li+ / Li, Ba2+ / Ba, Na+ / Na and Mg2+ / Mg are –3.05, –2.90, –2.71 and – 2.37 volt
respectively. Which one of the following is the strongest oxidizing agent?
(1) Ba2+
(2) Mg2+
(3) Na+
(4) Li+
Sol. Answer
(2)
Strongest oxidizing agent
Þ Highest reduction potential
Out of the given values, Mg2+ has the highest
reduction potential
38.
Which substance is serving as a reducing agent in the following reaction? 14H+ +
Cr2O7 2– +
3Ni ® 7H2 O + 3Ni2+ + Cr3+
(1) H+
(2) Cr2O72–
(3) H2O
(4) Ni
Sol. Answer
(4)
Cr ¾¾® Cr (Oxidizing agent)
Ni ¾¾® Ni2+ (Reducing agent)
i.e. Ni acts as
reducing agent since if reduces Cr+6 to Cr3+
39. The oxide, which cannot act as a reducing agent, is
(1) CO2
(2) ClO2
(3) NO2
(4) SO2
Sol. Answer (1)
Assertion-reasons type questions
CHOOSE APPROPRIATE ANSWER
(1) Both assertion and reason are correct statements, and reason is the correct explanation of the assertion.
(2) Both assertion and reason are correct statements, but reason is not the correct explanation of the assertion.
(3) Assertion is correct, but reason is wrong statement.
(4) Assertion is wrong, but reason is correct statement.
1. A : Fluorine acts as a stronger oxidising agent than chlorine.
R : Standard reduction potential of fluorine is higher than Cl2.
Sol. Answer (1)
Standard reduction potential of F2 is higher than that of Cl2. Fluorine is a stronger oxidizing agent than Cl2
2. A : Oxidation
number of carbon in HCN is +4.
R : Oxidation state and valency is same for carbon.
Sol. Answer (4)
3. A : The oxidation number of S is +6 in H2SO4
R : H2SO4 has one peroxide linkage.
Sol. Answer (3)
In H2SO4
+2(1) + x + 4 (–2) = 0
Þ x = +6
Oxidation state of sulphure = + 6
If does not have any peroxide linkage.
4. A : HNO2 acts as
reducing agent only.
R :
HNO2 oxidises to
HNO3 only but not
reduce by any reducing agent.
Sol.
Answer (4)
In HNO2,
oxidation state is +3 for nitrogen.
Hence
it can be oxidized to +5 or be reduced upto –3.
\ If can act as
both reducing as well as oxidizing agent.
5. A: In alkaline medium, KMnO4 acts as powerful oxidising agent.
R: KMnO4 reduces to give Mn2+ in alkaline medium.
Sol. Answer (3)
KMnO4 acts as a powerful oxidizing agent in both acidic and alkaline medium.
KMnO4 reduces to Mn+6 in alkaline medium.
6. A: When Cu2S is converted into Cu+ & SO2, then equivalent weight of Cu2S will be M/8 (M = Mol. wt. of Cu2S)
R : Cu+ is converted Cu++, during this one electrons is lost.
Answer (2)
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