Worksheetschemical reactions-oxidation,reduction,corrosion,rancidity
Total questions: 25
Worksheet time: 25mins
Name
Class
Date
1.
Oxidation involves:
a)
A)Gain of hydrogen
b)
B) Loss of oxygen
c)
C) Loss of hydrogen
d)
D) Loss of electrons
2.
In a redox reaction, the substance that gets reduced:
a)
A)Loses electrons
b)
B) Gains electrons
c)
C) Loses oxygen
d)
D) Gains hydrogen
3.
Which of the following is an example of oxidation?
a)
A)Cl₂ → 2Cl⁻
b)
B) Fe²⁺ → Fe³⁺
c)
C) Cu²⁺ → Cu
d)
D) H₂ → 2H⁺
4.
Which statement is correct for a redox reaction?
a)
A)Both oxidation and reduction occur separately
b)
B) Only oxidation occurs
c)
C) Oxidation and reduction occur simultaneously
d)
D) Only reduction occurs
5.
In the reaction:
Zn + CuSO₄ → ZnSO₄ + Cu, the reducing agent is:
a)
A)Zn
b)
B) Cu
c)
C) Cu²⁺
d)
D) SO₄²⁻
6.
What happens to the oxidation number of a substance when it is oxidized?
a)
A)Decreases
b)
B) Increases
c)
C) Remains same
d)
D) Doubles
7.
Which reaction shows reduction?
a)
A)Fe → Fe²⁺
b)
B) Cu → Cu²⁺
c)
C) O₂ → 2O²⁻
d)
D) H₂O → H₂
8.
What is the oxidizing agent in the reaction
2H₂ + O₂ → 2H₂O
a)
A)H₂
b)
B) O₂
c)
C) H₂O
d)
D) None
9.
In the redox reaction, the species which donates electrons is:
a)
A)Oxidising agent
b)
B) Reducing agent
c)
C) Catalyst
d)
D) Neutral
10.
Which is NOT true about redox reactions?
a)
A)Always involve transfer of electrons
b)
B) Always involve change in oxidation states
c)
C) Only occur in aqueous solutions
d)
D) Involve oxidation and reduction together
11.
Which of the following is a good oxidizing agent?
a)
A)H₂
b)
B) Na
c)
C) O₃
d)
D) Cl⁻
12.
In the reaction:
Cl₂ + 2NaBr → 2NaCl + Br₂
What is oxidized?
a)
A)Na
b)
B) Cl₂
c)
C) Br⁻
d)
D) Br₂
13.
Which of these can act as both oxidizing and reducing agent?
a)
A)H₂O₂
b)
B) Na
c)
C) Cl₂
d)
D) Both A and C
14.
Oxidising agents are substances that:
a)
A)Lose electrons
b)
B) Gain electrons
c)
C) Donate protons
d)
D) Accept protons
15.
Which substance is reduced in the reaction:
MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
a)
A)MnO₂
b)
B) HCl
c)
C) Cl⁻
d)
D) MnCl₂
16.
Corrosion of iron is:
a)
A)Physical change
b)
B) Reversible change
c)
C) Chemical change
d)
D) Change of state
17.
Which condition speeds up rusting?
a)
A) Dry air
b)
B) Oil coating
c)
C) Salt water
d)
D) Paint
18.
The brown coating on iron is called:
a)
A) Patina
b)
B) Verdigris
c)
C) Rust
d)
D) Tarnish
19.
Which method prevents corrosion of iron?
a)
A) Heating
b)
B) Galvanization
c)
C) Melting
d)
D) Electrolysis
20.
Corrosion of silver produces:
a)
A) Black Ag₂S
b)
B) Green CuCO₃
c)
C) Red Fe₂O₃
d)
D) Blue AgCl
21.
What is a common sign of rancidity?
a)
A) Color change
b)
B) Bubbles
c)
C) Sour smell and taste
d)
D) Burning
22.
Rancidity is mainly caused due to:
a)
A) Water absorption
b)
B) Microbial growth
c)
C) Oxidation of fats and oils
d)
D) Heating
23.
Which is used to prevent rancidity?
a)
A) Vinegar
b)
B) Antioxidants
c)
C) Salt
d)
D) Sugar
24.
Which food is more prone to rancidity?
a)
A) Boiled rice
b)
B) Sweets
c)
C) Fried chips
d)
D) Raw vegetables
25.
How can we delay rancidity?
a)
A) Store in open air
b)
B) Keep in sunlight
c)
C) Store in airtight containers
d)
D) Heat repeatedly
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