Final Assessment: Chemical Reactions and Equations

Section A: Chemical Change and Equations

Question 1mcq

Which is a chemical change?

A.Cutting paper

B.Burning of paper

C.Moving paper

D.Folding paper

Question 2mcq

In

2Na + Cl_2 \rightarrow 2NaCl

, the reactants are:

A.Only

2NaCl

B.

Na

and

Cl_2

C.Only

NaCl

D.

NaCl

and

Cl_2

Question 3mcq

A reaction in which a gas is produced may be shown by:

A.

(aq)

only

B.

\uparrow

C.

\downarrow

only

D.

=

only

Question 4mcq

Which is most likely a physical change?

A.Digestion of food

B.Evaporation of water

C.Burning of magnesium

D.Rusting of iron

Question 5mcq

The skeletal equation for calcium carbonate decomposing is:

A.

CaCO_3 \rightarrow Ca + O_2

B.

Ca + CO_3 \rightarrow CaO_2

C.

CaCO_3 \rightarrow CaO + CO_2

D.

CaO + CO_2 \rightarrow CaCO_3

Question 6mcq

The symbol

(s)

means:

A.Liquid

B.Solution in water

C.Gas

D.Solid

Question 7mcq

Which formula is correct for aluminium oxide?

A.

AlO

B.

AlO_3

C.

Al_3O_2

D.

Al_2O_3

Question 8mcq

A catalyst written above the arrow means it:

A.Stops the reaction permanently

B.Must be written as a reactant only

C.Is always the main product

D.Helps the reaction without being consumed overall

Question 9mcq

Iron reacts with oxygen to form iron oxide. The word equation is:

A.Iron + Oxygen

\rightarrow

Iron oxide

B.Iron + Iron oxide

\rightarrow

Oxygen

C.Iron oxide

\rightarrow

Iron + Oxygen

D.Oxygen

\rightarrow

Iron oxide + Iron

Question 10mcq

Which evidence best proves a new substance formed?

A.A solid is crushed

B.A liquid is poured

C.A wire is bent

D.A new solid with different properties appears

Section B: Balancing Chemical Equations

Question 11mcq

A balanced equation has equal numbers of:

A.Reactants only

B.Atoms of each element on both sides

C.Molecules only on left side

D.Products and arrows

Question 12mcq

Balance

Fe + S \rightarrow FeS

.

A.

2Fe + S \rightarrow FeS

B.

Fe + 2S \rightarrow FeS

C.

FeS \rightarrow Fe + S

D.

Fe + S \rightarrow FeS

Question 13mcq

Which is balanced?

A.

2Na + Cl_2 \rightarrow 2NaCl

B.

2Na + 2Cl_2 \rightarrow NaCl

C.

Na + Cl_2 \rightarrow NaCl

D.

Na + Cl \rightarrow NaCl_2

Question 14mcq

Balance

Fe + O_2 \rightarrow Fe_2O_3

.

A.

4Fe + O_2 \rightarrow 2Fe_2O_3

B.

4Fe + 3O_2 \rightarrow 2Fe_2O_3

C.

2Fe + O_2 \rightarrow Fe_2O_3

D.

Fe + O_2 \rightarrow Fe_2O_3

Question 15mcq

Balance

NaOH + H_2SO_4 \rightarrow Na_2SO_4 + H_2O

.

A.

NaOH + H_2SO_4 \rightarrow Na_2SO_4 + H_2O

B.

NaOH + 2H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O

C.

2NaOH + H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O

D.

2NaOH + H_2SO_4 \rightarrow Na_2SO_4 + H_2O

Question 16mcq

Balance

C_2H_6 + O_2 \rightarrow CO_2 + H_2O

.

A.

C_2H_6 + 2O_2 \rightarrow 2CO_2 + 3H_2O

B.

C_2H_6 + 7O_2 \rightarrow CO_2 + H_2O

C.

2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O

D.

2C_2H_6 + 5O_2 \rightarrow 4CO_2 + 6H_2O

Question 17mcq

Which action is allowed while balancing?

A.Changing

H_2O

to

HO

B.Changing

O_2

to

O_3

C.Removing products

D.Changing coefficients before formulae

Question 18mcq

If total mass of reactants is 18 g, total mass of products in a closed system is:

A.18 g

B.36 g

C.0 g

D.9 g

Question 19mcq

Balance

Al + Cl_2 \rightarrow AlCl_3

.

A.

2Al + 3Cl_2 \rightarrow 2AlCl_3

B.

3Al + 2Cl_2 \rightarrow AlCl_3

C.

2Al + Cl_2 \rightarrow 2AlCl_3

D.

Al + Cl_2 \rightarrow AlCl_3

Question 20mcq

A balanced equation is more informative than a skeletal equation because it shows:

A.Only smell of products

B.Only colour of products

C.Correct relative number of reactant and product particles

D.Only laboratory temperature

Section C: Reaction Types and Energy

Question 21mcq

2Mg + O_2 \rightarrow 2MgO

is a:

A.Combination reaction

B.Decomposition reaction

C.Precipitation only

D.Double displacement reaction

Question 22mcq

2AgCl \xrightarrow{sunlight} 2Ag + Cl_2

is:

A.Thermal decomposition

B.Photolytic decomposition

C.Combination

D.Double displacement

Question 23mcq

Zn + CuSO_4 \rightarrow ZnSO_4 + Cu

is:

A.Double displacement

B.Combination

C.Displacement reaction

D.Decomposition

Question 24mcq

HCl + NaOH \rightarrow NaCl + H_2O

is best classified as:

A.Double displacement reaction

B.Photolytic decomposition

C.Single displacement

D.Combination only

Question 25mcq

The formation of

BaSO_4(s)

from two solutions is an example of:

A.Precipitation

B.Combustion

C.Melting

D.Sublimation

Question 26mcq

Which reaction type is shown by

AB + CD \rightarrow AD + CB

?

A.Double displacement

B.Combination

C.Decomposition

D.Single displacement

Question 27mcq

Burning of a candle is mainly:

A.Electrolytic decomposition

B.Exothermic

C.Neutral only

D.Endothermic

Question 28mcq

CaCO_3 + heat \rightarrow CaO + CO_2

is:

A.Precipitation reaction

B.Displacement reaction

C.Endothermic decomposition

D.Exothermic combination

Question 29mcq

If a reaction absorbs heat from surroundings, the surroundings may feel:

A.Brighter only

B.Hotter always

C.Cooler

D.No change is possible

Question 30mcq

Which pair correctly shows opposite reaction patterns?

A.Precipitation and corrosion

B.Combination and decomposition

C.Rancidity and crystallisation

D.Displacement and combustion

Section D: Redox, Corrosion and Rancidity

Question 31mcq

Gain of oxygen is called:

A.Precipitation

B.Oxidation

C.Filtration

D.Reduction

Question 32mcq

Loss of oxygen is called:

A.Oxidation

B.Rancidity

C.Reduction

D.Combination

Question 33mcq

In

CuO+H_2\rightarrow Cu+H_2O

, copper oxide is:

A.A gas

B.Reduced

C.A catalyst

D.Oxidised

Question 34mcq

In

CuO+H_2\rightarrow Cu+H_2O

, hydrogen is:

A.Oxidised

B.Unchanged

C.Reduced

D.A precipitate

Question 35mcq

Rusting is faster when iron is exposed to:

A.Moist air

B.Vacuum

C.Dry nitrogen

D.Pure oil only

Question 36mcq

Which is the best rust-prevention method for an iron bridge?

A.Painting or galvanising the surface

B.Washing it with salt water daily

C.Scratching off paint frequently

D.Keeping it wet

Question 37mcq

Rancidity is caused by oxidation of:

A.Pure water

B.Glass

C.Table salt

D.Fats and oils

Question 38mcq

Which helps prevent rancidity in packed chips?

A.Flushing the packet with nitrogen

B.Keeping it in sunlight

C.Leaving the packet open

D.Adding more oxygen

Question 39mcq

In

Fe_2O_3 + 2Al \rightarrow Al_2O_3 + 2Fe

, aluminium is:

A.A solvent

B.Reduced

C.Oxidised

D.A precipitate

Question 40mcq

Why do antioxidants help preserve food?

A.They add oxygen quickly

B.They change food into metal

C.They make food rust

D.They slow oxidation of fats and oils