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Worksheets

Chemical Reactions And Equations_LS_14

Total questions: 58

Worksheet time: 2hrs 39mins

Name
Class
Date
1.
If in a reaction, copper is reduced; its number of electrons has:
a)
Increased
b)
Decreased
c)
Remained Constant
d)
Varies Randomly
2.
Is calcium oxidized or reduced in the following reaction? 
2CaO--> 2Ca + O2
a)
Oxidized
b)
Reduced
3.

What element is being Oxidized?

a)

N+5

b)

H+1

c)

O-2

d)

S-2

4.

What element is being Reduced?

a)

N+5

b)

H+1

c)

O-2

d)

S-2

5.

What element is being Oxidized?

a)

I0

b)

H+1

c)

S+4

d)

O-2

6.

What element is being reduced?

a)

I0

b)

H+1

c)

S+4

d)

O-2

7.
If an atom loses electrons during a chemical reaction, the atom was:
a)
Oxidized
b)
Reduced
c)
Neutralized
d)
Precipitated
8.

In the reaction Zn + H2O --> ZnO2 + H2

which element, if any, is oxidized?

a)

Zn0

b)

Zn+2

c)

O-2

d)

H20

e)

None

9.
What substance is oxidized in the following reaction?
4Fe + 3O2 --> 2Fe2O3
a)
Iron
b)
Fluorine
c)
Oxygen
10.

Cl2 + 2e- --> 2Cl - is an example of:

a)

a chemical reaction

b)

redox

c)

oxidation

d)

reduction

11.

An increase in oxidation number.

a)

more acidic

b)

reduction

c)

less basic

d)

oxidation

12.

A decrease in oxidation number.

a)

redox

b)

reduction

c)

oxidation

d)

dilute

13.

Oxidation-reduction reactions occur because of the competition between particles for...

a)

protons

b)

neutrons

c)

electrons

d)

positrons

14.

Mg + PbCl2 --> MgCl2 + Pb. Which statement correctly describes the oxidation and reduction that occur?

a)

Mg is oxidized and Cl- is reduced

b)

Mg is oxidized and Pb+2 is reduced

c)

Mg is reduced and Cl- is oxidized

d)

Mg is reduced and Pb+2 is oxidized

15.

As an element is oxidized, its oxidation number...

a)

increases as electrons are gained

b)

decreases as electrons are gained

c)

decreases as electrons are lost

d)

increases as electrons are lost

16.

When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced ? Why ?

2Mg + O2⟶ 2MgO

a)

Magnesium is oxidised as addition of oxygen to magnesium takes place leading to formation of magnesium oxide.

b)

Magnesium is reduced as addition of hydrogen to magnesium takes place leading to formation of magnesium oxide.

17.

In the reaction represented by the equation :

MnO2​+4HCl→MnCl2​+2H2​O+Cl2​

name the substance oxidised. 

a)

HCl is oxidised to Cl2​.

b)

MnO2​ is the oxidising agent.

c)

MnO2​ is reduced to MnCl2​.

d)

HCl is the reducing agent.

18.

In the reaction represented by the equation :

MnO2​+4HCl→MnCl2​+2H2​O+Cl2​

name the oxidising agent.

a)

HCl is oxidised to Cl2​.

b)

MnO2​ is the oxidising agent.

c)

MnO2​ is reduced to MnCl2​.

d)

HCl is the reducing agent.

19.

In the reaction represented by the equation :

MnO2​+4HCl→MnCl2​+2H2​O+Cl2​

name the substance reduced. 

a)

HCl is oxidised to Cl2​.

b)

MnO2​ is the oxidising agent.

c)

MnO2​ is reduced to MnCl2​.

d)

HCl is the reducing agent.

20.

In the reaction represented by the equation :

MnO2​+4HCl→MnCl2​+2H2​O+Cl2​

name the reducing agent.

a)

HCl is oxidised to Cl2​.

b)

MnO2​ is the oxidising agent.

c)

MnO2​ is reduced to MnCl2​.

d)

HCl is the reducing agent.

21.

Two Reactants and One Product

a)

Decomposition

b)

Synthesis

c)

Combustion

d)

Single Replacement

22.

What is the type of reaction shown above?

a)

Synthesis

b)

Decomposition

c)

Single Replacement

d)

Double Replacement

23.

A chemical change in which two substances react to form a new substance is a ____________________________.

a)

decomposition reaction

b)

Combination reaction

c)

precipitation reaction

d)

combustion reaction

24.
In an exothermic reaction, heat is ...
a)
taken in
b)
given out
25.
If a chemical reaction is EXOTHERMIC, the temperature would....
a)
Stay the same
b)
Increase
c)
Decrease
26.

When magnesium ribbon burns in the presence of oxygen it produces:

a)

magnesium iodide

b)

magnesium chloride

c)

magnesium oxide

d)

none

27.
HCl reacts with Zn giving off heat
a)
endothermic
b)
exothermic
28.

Which of the following is an example of combination reaction? Select all that apply.

a)

Na + Br2 → NaBr

b)

KClO3 → KCl + O2

c)

HgO + Cl2 HgCl + O2

d)

2 Mg+O2 → 2MgO

e)

Ca + I2 → CaI2

29.

Burning of carbon in presence of oxygen to produce carbon dioxide is an example of a combination reaction which is also an _______ reaction.

C (s) + O2 (g) →CO2 + Heat

a)

Exothermic

b)

Endothermic

30.

Reaction of Nitrogen with oxygen to give nitrous oxide is an example of a combination reaction which is also an _____ reaction.

N2 (g) + O(g) + Heat → 2NO (g)

a)

Exothermic

b)

Endothermic

31.

Reduction is the ___________ of electrons.

a)

loss

b)

gain

c)

sharing

d)

transfer

32.

Oxidation is the _________ of electrons.

a)

loss

b)

gain

c)

sharing

d)

transfer

33.

Gaining hydrogen is an example of...

a)

oxidation

b)

reduction

34.

Gaining oxygen is an example of...

a)

oxidation

b)

reduction

35.

In a redox reaction, the species reduced

a)

gains electrons and is the oxidizing agent

b)

loses electrons and is the oxidizing agent

c)

loses electrons and is the reducing agent

d)

gains electrons and is the reducing agent

36.
Which statement is true:
Mg → Mg2+ + 2e
a)
Mg gains 2 electrons
b)
Mg2+ loses 2 electrons
c)
Mg loses 1 electron
d)
Mg loses 2 electrons
37.
In the reaction
2Ca(s) + O2(g) --> 2CaO(s), calcium is __________
a)
Reduced
b)
Synthesized
c)
Oxidized
d)
None of the above
38.

Is oxidation an exothermic or an endothermic reaction?

a)

Oxidation reaction is an exothermic reaction as heat is released during this reaction

b)

Oxidation reaction is an endothermic reaction as heat is released during this reaction

39.

Explain, by giving an example, how oxidation and reduction proceed side by side.

a)

CuO + H→ Cu + H2O    In this reaction, CuO gets reduced to Cu by losing oxygen and H2 gets oxidized to H2O by gaining oxygen. Hence, oxidation and reduction proceed side by side.

b)

2Na(s) + Cl2(g)------> 2NaCl(s)

Here Na loses electrons and gets oxidised and Cl gains the same electrons to be reduced. So, both oxidation and reduction occur simultaneously in a given reaction.

 

c)

C(s) + 2H2(g) → CH4(g)

d)

Cu2++Zn⇌Cu+Zn2+, Zn is oxidized to Zn2+ and Cu2+ is reduced to Cu.

40.

What is the colour of ferrous sulphate crystals ?

a)

Green

b)

Ochre

c)

Olive

d)

Juniper

41.

How does the colour of ferrous sulphate crystals change after heating?

a)

Green

b)

Ochre

c)

Olive

d)

Juniper

e)

Brown

42.

Name the product formed on strongly heating ferrous sulphate crystals.

a)

ferric oxide

b)

ferrous oxide

c)

ferrosoferric oxide

d)

ferroferric oxide

43.

Name the product formed on strongly heating ferrous sulphate crystals.

a)

ferric oxide

b)

ferrous oxide

c)

ferrosoferric oxide

d)

ferroferric oxide

44.

Name the product formed on strongly heating ferrous sulphate crystals.

a)

Combination Reaction. .

b)

Decomposition Reaction

c)

Displacement Reaction.

d)

Double Displacement Reaction.

e)

Precipitation Reaction.

45.

Decomposition Reaction. What is the first statement of the video clip?

a)

Decomposition Reactions:

the reaction in which a single compound

breaks up into two or more simple substances is known as

reactions

b)

The decomposition reaction generally takes place when energy in some form such as heat, electricity or light is

supplied to the reactants

c)

CaCO3(s)+heat (when heated) → CaO(s) + CO2(g)

d)

decomposition of a substance by heating is thermal decomposition

e)

Electrolysis: the decomposition of a substance by passing electric current through it is

known as electrolysis

46.

Decomposition Reaction. What is the second statement of the video clip?

a)

2 NaCl(l) (electrolysis) ---> 2 Na(l) + Cl2(g)

Sodium chloride on passing electric current gives sodium 2na and chlorine cl2

b)

The decomposition reaction generally takes place when energy in some form such as heat, electricity or light is

supplied to the reactants

c)

CaCO3(s)+heat (when heated) → CaO(s) + CO2(g)

d)

decomposition of a substance by heating is thermal decomposition

e)

Electrolysis: the decomposition of a substance by passing electric current through it is

known as electrolysis

47.

Decomposition Reaction. What is the third statement of the video clip?

a)

2 NaCl(l) (electrolysis) ---> 2 Na(l) + Cl2(g)

Sodium chloride on passing electric current gives sodium 2na and chlorine cl2

b)

Photolysis: the decomposition of a compound with light is called photolysis

c)

CaCO3(s)+heat (when heated) → CaO(s) + CO2(g)

d)

decomposition of a substance by heating is thermal decomposition

e)

Electrolysis: the decomposition of a substance by passing electric current through it is

known as electrolysis

48.

Decomposition Reaction. What is the fourth statement of the video clip?

a)

2 NaCl(l) (electrolysis) ---> 2 Na(l) + Cl2(g)

Sodium chloride on passing electric current gives sodium 2na and chlorine cl2

b)

Photolysis: the decomposition of a compound with light is called photolysis

c)

study of decomposition of silver chloride: take about 2 grams of silver chloride in

a china dish

d)

decomposition of a substance by heating is thermal decomposition

e)

Electrolysis: the decomposition of a substance by passing electric current through it is

known as electrolysis

49.

Decomposition Reaction. What is the fifth statement of the video clip?

a)

2 NaCl(l) (electrolysis) ---> 2 Na(l) + Cl2(g)

Sodium chloride on passing electric current gives sodium 2na and chlorine cl2

b)

Photolysis: the decomposition of a compound with light is called photolysis

c)

study of decomposition of silver chloride: take about 2 grams of silver chloride in

a china dish

d)

place this china dish in the sunlight for sometime

e)

Electrolysis: the decomposition of a substance by passing electric current through it is

known as electrolysis

50.

Decomposition Reaction. What is the sixth statement of the video clip?

a)

2 NaCl(l) (electrolysis) ---> 2 Na(l) + Cl2(g)

Sodium chloride on passing electric current gives sodium 2na and chlorine cl2

b)

Photolysis: the decomposition of a compound with light is called photolysis

c)

study of decomposition of silver chloride: take about 2 grams of silver chloride in

a china dish

d)

place this china dish in the sunlight for sometime

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

51.

Decomposition Reaction. What is the seventh statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

Photolysis: the decomposition of a compound with light is called photolysis

c)

study of decomposition of silver chloride: take about 2 grams of silver chloride in

a china dish

d)

place this china dish in the sunlight for sometime

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

52.

Decomposition Reaction. What is the eighth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

study of decomposition of silver chloride: take about 2 grams of silver chloride in

a china dish

d)

place this china dish in the sunlight for sometime

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

53.

Decomposition Reaction. What is the ninth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

place this china dish in the sunlight for sometime

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

54.

Decomposition Reaction. What is the tenth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

the above reactions are used in black and white photography

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

55.

Decomposition Reaction. What is the eleventh statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

the above reactions are used in black and white photography

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

56.

Decomposition Reaction. What is the Twelfth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

the above reactions are used in black and white photography

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

57.

Decomposition Reaction. What is the Thirteenth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

the above reactions are used in black and white photography

e)

it is observed that the white silver chloride turns gray on exposure to sunlight

58.

Decomposition Reaction. What is the Fourteenth statement of the video clip?

a)

2AgCl (on exposure to sunlight) ---- 2Ag +Cl2

b)

silver bromide undergoes decomposition when exposed to light

c)

2AgBr (when exposed to light) ----> 2Ag +Br2

d)

the above reactions are used in black and white photography

e)

it is observed that the white silver chloride turns gray on exposure to sunlight