Chemical Reactions
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Physical and chemical changes
SubtopicPhysical and chemical changes under Chemical Reactions for Grade 11 IGCSE.
Preview questions (no answers)
- 1.
Which of the following is a physical change involving the removal of heat?
A.Boiling
B.Evaporating
C.Freezing
D.Sublimating
- 2.
Heating copper(II) carbonate causes it to turn from green to black as it releases carbon dioxide gas. This process is a:
A.Physical change
B.Chemical change
C.Melting process
D.Sublimation process
- 3.
In which of these scenarios is a physical change occurring?
A.A piece of fruit rotting
B.A car engine burning gasoline
C.A block of lead being hammered into a thin sheet
D.A copper roof turning green over many years
- 4.
What type of change occurs when a battery powers a flashlight?
A.Physical change inside the battery
B.Chemical change inside the battery
C.A change of state of the battery acid
D.A sublimation of the electrodes
- 5.
When anhydrous cobalt(II) chloride paper turns from blue to pink in the presence of water vapor, what is occurring?
A.A physical change because the water can be evaporated to turn it blue again.
B.A chemical change because a hydrated compound is formed with new properties.
C.A physical change because the color change is only on the surface.
D.A chemical change because the water molecules are destroyed.
- 6.
Which statement correctly identifies a chemical change involving food?
A.Slicing an apple into four pieces.
B.Freezing berries to preserve them.
C.The browning of an apple slice when exposed to air.
D.Mixing grapes and melon in a fruit salad.
- 7.
During the Haber process, nitrogen and hydrogen are reacted under high pressure. If the pressure is increased, the molecules move closer together. This specific effect of pressure (moving molecules closer) is a:
A.Physical change.
B.Chemical change.
C.Nuclear change.
D.Biological change.
- 8.
The diagram illustrates the 'Contact Process' for making sulfuric acid. Which stage represents a physical change?
A.Stage 1
B.Stage 2
C.Stage 3
D.Stage 4
- 9.
Which of the following is the best evidence that the digestion of starch by amylase in the mouth is a chemical change?
A.The starch is broken down into smaller pieces by the teeth.
B.The starch is mixed with saliva to form a bolus.
C.The starch is converted into maltose, which reacts differently with Benedict's solution than starch does.
D.The starch changes its shape to fit down the esophagus.
- 10.
A student adds a piece of zinc to a solution of copper(II) sulfate. The blue color fades, and a brown solid forms. What type of change is this and why?
A.Physical change because the zinc is just being coated with copper.
B.Chemical change because zinc atoms are being oxidized to ions and ions are being reduced to copper atoms.
C.Physical change because the total number of ions in the solution remains the same.
D.Chemical change because the solution gets colder during the reaction.
Download the worksheet for Chemical Reactions - Physical and chemical changes to practice offline. It includes additional chapter-level practice questions.
Rate of reaction (Concentration, Temperature, Surface area, Catalysts)
SubtopicRate of reaction (Concentration, Temperature, Surface area, Catalysts) under Chemical Reactions for Grade 11 IGCSE.
Preview questions (no answers)
- 1.
Which change increases the number of particles in a given volume of solution?
A.Adding more solvent
B.Increasing the concentration
C.Increasing the temperature
D.Using a larger flask
- 2.
What does it mean if the line on a volume-time graph for a reaction becomes horizontal?
A.The reaction is at its fastest
B.The reaction has finished
C.The temperature is increasing
D.The catalyst is working well
- 3.
If you double the mass of a solid reactant but its surface area stays the same, how will the initial rate change?
A.It will double
B.It will stay the same
C.It will decrease
D.It will triple
- 4.
Which of the following describes a 'successful' collision?
A.Any collision between particles
B.A collision that does not lead to a reaction
C.A collision that leads to the formation of products
D.A collision where particles bounce off each other
- 5.
Which statement is true for an exothermic reaction when a catalyst is added?
A.The activation energy for the forward reaction decreases.
B.The energy of the reactants increases.
C.The energy of the products decreases.
D.The reaction becomes endothermic.
- 6.
When measuring the rate of a reaction that produces a gas, why is the 'initial rate' usually the fastest?
A.The temperature is highest at the start.
B.The concentration of the reactants is at its maximum.
C.The catalyst is most active at the beginning.
D.The gas syringe has no friction at the start.
- 7.
Which of the following is a biological catalyst?
A.A hormone
B.An enzyme
C.A vitamin
D.A carbohydrate
- 8.
A catalyst is used in the Haber process. Which of the following is the catalyst used?
A.Vanadium(V) oxide
B.Iron
C.Platinum
D.Manganese(IV) oxide
- 9.
Which experimental data would allow you to calculate the initial rate of a reaction most accurately?
A.The time taken for the reaction to stop.
B.The total volume of gas produced at the end.
C.Multiple measurements of concentration at short time intervals near the start.
D.The temperature of the reaction mixture at the end.
- 10.
For a reaction to occur, which of the following is absolutely necessary according to collision theory?
A.Molecules must collide.
B.Molecules must be in the same phase.
C.A catalyst must be present.
D.The reaction must be exothermic.
Download the worksheet for Chemical Reactions - Rate of reaction (Concentration, Temperature, Surface area, Catalysts) to practice offline. It includes additional chapter-level practice questions.
Reversible reactions and dynamic equilibrium
SubtopicReversible reactions and dynamic equilibrium under Chemical Reactions for Grade 11 IGCSE.
Preview questions (no answers)
- 1.
If the concentration of a reactant is decreased, in which direction will the equilibrium shift?
A.To the left
B.To the right
C.It will not shift
D.The reaction will explode
- 2.
What color is hydrated copper(II) sulfate?
A.Blue
B.White
C.Green
D.Yellow
- 3.
What is the purpose of using a catalyst in a reversible industrial process like the Contact process?
A.To reach equilibrium faster
B.To increase the total amount of product at equilibrium
C.To change the direction of the reaction
D.To stop the backward reaction from happening
- 4.
In the reaction , which side has the smaller volume of gas?
A.The product side (right)
B.The reactant side (left)
C.Both sides have the same volume
D.Volumes cannot be compared
- 5.
Nitrogen dioxide () is a brown gas that exists in dynamic equilibrium with dinitrogen tetroxide (), which is a colorless gas. The chemical equation for this reversible reaction is shown below:
Based on the logic in the provided diagram, which combination of changes will shift the equilibrium position to favor the formation of ?
A.Decreasing the temperature and increasing the pressure
B.Increasing the temperature and decreasing the pressure
C.Increasing the temperature and increasing the pressure
D.Decreasing the temperature and decreasing the pressure
- 6.
In the reaction , there are 5 moles of gas on the left and 4 moles of gas on the right. How does increasing the pressure affect this system?
A.It shifts the equilibrium to the right to favor the side with fewer gas molecules.
B.It shifts the equilibrium to the left to favor the side with more gas molecules.
C.It has no effect on the position of equilibrium.
D.It decreases the rate of the forward reaction.
- 7.
Consider the equilibrium: . What happens to the color if sodium hydroxide () is added?
A.The solution becomes more yellow as is removed.
B.The solution becomes more orange as is added.
C.The solution turns green.
D.There is no color change because is not in the equation.
- 8.
In the reaction , the initial pressure is . At equilibrium, the pressure is . Which statement is correct?
A.The moles of gas have increased.
B.The reaction has shifted to the right.
C.The reaction is exothermic.
D.A catalyst was used to decrease the pressure.
- 9.
Which of the following statements about a reaction with a very large value () is true?
A.The reaction is very fast.
B.The reaction is virtually irreversible and goes almost to completion.
C.The equilibrium mixture consists mostly of reactants.
D.The reaction must be exothermic.
- 10.
What happens to the equilibrium in a closed container if the volume of the container is increased at constant temperature?
A.The pressure of decreases and stays lower.
B.More evaporates until the pressure of returns to its original value.
C.The equilibrium constant increases.
D.The amount of increases.
Download the worksheet for Chemical Reactions - Reversible reactions and dynamic equilibrium to practice offline. It includes additional chapter-level practice questions.
Le Chatelier’s principle
SubtopicLe Chatelier’s principle under Chemical Reactions for Grade 11 IGCSE.
Preview questions (no answers)
- 1.
If a reaction is at equilibrium and the temperature is increased, the system will shift to:
A.Absorb the extra heat
B.Release more heat
C.Decrease the pressure
D.Increase the concentration of all species
- 2.
A system at equilibrium is in a 'closed' container. What does this mean?
A.No heat can enter or leave
B.No matter can enter or leave
C.The pressure is always 1 atm
D.The container is transparent
- 3.
In a reversible reaction, if the forward reaction is exothermic, the reverse reaction must be:
A.Exothermic
B.Endothermic
C.At equilibrium
D.Faster
- 4.
For the equilibrium , which side has the higher pressure at constant volume (more moles of gas)?
A.The side
B.The side
C.Both sides are equal
D.Pressure is zero
- 5.
For the gaseous reaction , which statement is true regarding pressure changes?
A.An increase in pressure shifts the equilibrium to the left
B.An increase in pressure shifts the equilibrium to the right
C.A decrease in pressure shifts the equilibrium to the left
D.Pressure changes have no effect as all are gases
- 6.
If the forward reaction of a reversible process is endothermic, what does the sign of the reverse reaction represent?
A.It is negative, meaning the reverse reaction is exothermic
B.It is positive, meaning the reverse reaction is endothermic
C.It is zero, because the system is at equilibrium
D.It depends on the concentration of the reactants
- 7.
What is the effect of adding more water to the equilibrium: ?
A.The equilibrium shifts to the left, decreasing the yield of the ester
B.The equilibrium shifts to the right, increasing the yield of the ester
C.There is no effect because all substances are liquids
D.The rate of the forward reaction increases
- 8.
In the decomposition of hydrogen peroxide: , why is it not possible to reach a state of dynamic equilibrium in an open beaker?
A.The gas escapes, preventing the reverse reaction from occurring.
B.The reaction is too fast to reach equilibrium.
C.The water evaporates, changing the concentration.
D.The reaction is not reversible.
- 9.
For the reaction (where represents heat), which of the following will result in an increase in the number of moles of at equilibrium?
A.Increasing the temperature
B.Increasing the pressure
C.Removing from the system
D.Adding a catalyst
- 10.
In the equilibrium , if the pressure is increased, the equilibrium shifts to the right. What happens to the rate of the reverse reaction after the shift?
A.It increases because the concentration of has increased.
B.It decreases because the equilibrium shifted away from it.
C.It remains the same because only the forward rate was affected.
D.It decreases because the volume is smaller.
Download the worksheet for Chemical Reactions - Le Chatelier’s principle to practice offline. It includes additional chapter-level practice questions.
Redox reactions (Oxidation states and identifying agents)
SubtopicRedox reactions (Oxidation states and identifying agents) under Chemical Reactions for Grade 11 IGCSE.
Preview questions (no answers)
- 1.
In a redox reaction, the total number of electrons lost must be:
A.Greater than electrons gained
B.Less than electrons gained
C.Equal to electrons gained
D.Zero
- 2.
What is the oxidation state of Oxygen in Hydrogen peroxide ()?
A.-2
B.0
C.-1
D.+1
- 3.
During the oxidation of a metal, the metal atom usually:
A.Gains electrons to form an anion
B.Loses electrons to form a cation
C.Gains protons
D.Shares electrons with another metal
- 4.
What is the charge/oxidation state of an Alkali Metal ion in a compound?
A.+1
B.+2
C.-1
D.0
- 5.
Which of the following half-equations correctly shows the oxidation of sodium metal?
A.B.C.D. - 6.
What is the oxidation state of Carbon () in sodium hydrogencarbonate, ?
A.+2
B.+3
C.+4
D.+5
- 7.
Identify the oxidizing agent in the reaction: .
A.B.C.D. - 8.
Identify the element whose oxidation state remains unchanged in the reaction: .
A.Sulfur
B.Oxygen
C.Hydrogen
D.Both Hydrogen and Oxygen
- 9.
What is the oxidation state of Manganese in ?
A.+2
B.+4
C.+6
D.+7
- 10.
In the reaction , how many moles of act as an oxidizing agent per mole of copper?
A.4
B.2
C.1
D.3
Download the worksheet for Chemical Reactions - Redox reactions (Oxidation states and identifying agents) to practice offline. It includes additional chapter-level practice questions.