REDOX AND EQUIVALENT CONCEPT QUIZ-16

REDOX AND EQUIVALENT CONCEPT QUIZ-16

Dear Readers,

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Q1. Weight of FeSO₄ (mol.wt.=152) oxidized by 200 mL of 1 N KMnO₄ solution is :

•  30.4 g
•  15.2 g
•  60.8 g
•  158 g

Solution
Meq.of FeSO₄=Meq.of KMnO₄ w/(152/1)× 1000=200 × 1 ∴w=30.4 g

Q2.Oxidation state of chromium

•  +10
•  +6
•  +3
•  +2

Solution

It is chromium peroxide. Let the oxidation number of Cr is ^''x^''. Cr^(x+)+O₂^-+O^(2-)+O₂^--CrO₅ x+(-1)2+(-1)2+(-2)1=0 x-6=0 x=+6 Hence, the oxidation state of Cr is +6.

Q3.  What volume of 0.1 N oxalic acid solution can be reduced by 250 g of an 8 per cent by weight KMnO₄ solution?

•   6.3 litre
•  12.6 litre
•  25.2 litre
•  0.63 litre

Solution
Meq.of oxalic acid=Meq.of KMnO₄ V × 0.1 (250 × 8)/(100 × 31.6) × 1000=6.3 litre

Q4. The number of mole of KMnO₄ that will be needed to react completely with one mole of ferrous oxalate in acidic solution is :

•  3/5
•  2/5
•  4/5
•  1

Solution
Mn⁽⁷⁺⁾+5e ⟶Mn⁽²⁺⁾ Fe⁽²⁺⁾⟶Fe^{(3+ )}+e C₂^{(3+ )} ⟶2C⁽⁴⁺⁾+2e

Q5.A substance, that by its sharp colour change indicates the completion of reaction is known as :

•  Acid
•  Base
•  Indicator
•  None of these

Solution
 Indicators are the substances which indicates the completion of a reaction.

Q6. The oxidation state of iron in sodium nitroprusside is :

•  +2
•  +1
• Zero
•  +3

Solution
Na₂ [Fe(CN)₅ NO]

Q7. Oxidation of thiosulphate (S₂ O₃^(2-)) ions by iodine gives:

•  SO₃^-
•  SO₄^(2-)
•  S₄ O₆^(2-)
•  S₂ O₈^(2-)

Solution
2S₂ O₃^(2-)+I₂ ⟶S₄ O₆^(2-)+2I^-

Q8.What volume of 2N K₂ Cr₂ O₇ solution is required to oxidise 0.81 g of H₂ S in acidic medium?

•  47.8 mL
•  T23.8 mL
•  40 mL
•  72 mL

Solution
Meq.of K₂ Cr₂ O₇=Meq.of H₂ S 2 x V=0.81/(34/2) x 1000 ∴V=23.8 mL

Q9.The oxidation number of oxygen in KO₃,Na₂ O₂ is

•  3,2
•  1,0
•  0,1
•  -0.33,-1

Solution
KO₃ Na₂ O₂ Suppose O.N. of O = x suppose O.N. of O = x +1+3x=0 2×1+2x=0 3x= -1 2+2x= 0 x=-1/3 2x=-2 x=-0.33 x=-2/2 x= -1

Q10. Elements which generally exhibit multiple oxidation states and whose ions are coloured are known as :

•  Metalloid
•  Non-metals
•  Metals
• Transition metals

Solution
A characteristic property of transition elements.