Chemical Reactions questions

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Chemical Reactions question collection

Review Chemical Reactions questions for Chemistry, with correct answers shown and coverage across what defines a chemical change; choosing which observation is good evidence that a chemical reaction has happened; choosing which equation is balanced for magnesium burning in oxygen.

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Question 1

What defines a chemical change?
  1. New substances are formed
  2. Only the state changes
  3. Two liquids are mixed
  4. A solid changes shape

Question 2

Which observation is good evidence that a chemical reaction has happened?
  1. A gas is produced
  2. Ice melts in warm air
  3. Water boils when heated
  4. Sugar dissolves in water

Question 3

Which equation is balanced for magnesium burning in oxygen?
  1. \(2\mathrm{Mg} + \mathrm{O}_{2} \to 2\mathrm{MgO}\)
  2. \(\mathrm{Mg} + \mathrm{O}_{2} \to \mathrm{MgO}\)
  3. \(2\mathrm{Mg} + 2\mathrm{O}_{2} \to 2\mathrm{MgO}\)
  4. \(\mathrm{Mg} + \mathrm{O} \to \mathrm{MgO}_{2}\)

Question 4

What does an acid usually produce when it reacts with a metal?
  1. A salt and hydrogen
  2. A salt and oxygen
  3. A base and carbon dioxide
  4. Water

Question 5

What are the products when an acid reacts with an alkali?
  1. A salt and water
  2. A salt and hydrogen
  3. A metal oxide and water
  4. A metal and water

Question 6

Which observation can be evidence of a chemical reaction?
  1. A lasting colour change
  2. A solid being cut smaller
  3. Ice changing into water
  4. Sugar dissolving without colour change

Question 7

What colour does blue litmus become in an acid?
  1. Red
  2. Blue
  3. Green
  4. Purple

Question 8

What colour does red litmus become in an alkali?
  1. Blue
  2. Red
  3. Yellow
  4. Orange

Question 9

In terms of oxygen, what is oxidation?
  1. Gain of oxygen
  2. Loss of oxygen
  3. Gain of electrons
  4. Loss of protons

Question 10

In terms of oxygen, what is reduction?
  1. Loss of oxygen
  2. Gain of oxygen
  3. No change in oxygen
  4. Sharing of oxygen

Question 11

What happens in a displacement reaction?
  1. A more reactive element replaces a less reactive one
  2. A less reactive element replaces a more reactive one
  3. Two elements combine into one compound
  4. One compound splits into simpler substances

Question 12

What happens when magnesium enters copper sulfate solution?
  1. Magnesium atoms displace copper ions
  2. Copper atoms displace magnesium ions
  3. Both metals remain in solution unchanged
  4. Copper and magnesium form an alloy

Question 13

Which metal is more likely to react vigorously with dilute hydrochloric acid?
  1. Magnesium
  2. Copper
  3. Silver
  4. Gold

Question 14

What forms when calcium carbonate thermally decomposes?
  1. Calcium oxide and carbon dioxide
  2. Calcium metal and oxygen
  3. Calcium hydroxide and carbon
  4. Calcium oxide and oxygen

Question 15

Which word equation shows neutralisation?
  1. \(\text{Hydrochloric acid} + \text{sodium hydroxide} \to \text{sodium chloride} + \text{water}\)
  2. \(\text{Hydrochloric acid} + \text{zinc} \to \text{zinc chloride} + \text{hydrogen}\)
  3. \(\text{Methane} + \text{oxygen} \to \text{carbon dioxide} + \text{water}\)
  4. \(\text{Copper carbonate} \to \text{copper oxide} + \text{carbon dioxide}\)

Question 16

What forms in complete combustion of a hydrocarbon?
  1. Carbon dioxide and water
  2. Carbon monoxide and water
  3. Carbon and hydrogen
  4. Methane and oxygen

Question 17

What is thermal decomposition?
  1. A compound breaking down when heated
  2. Two elements joining when cooled
  3. A solid melting when heated
  4. A metal replacing another element

Question 18

What does a catalyst do?
  1. Increases reaction rate without being used up
  2. Increases product yield by becoming a reactant
  3. Decreases reaction rate without changing yield
  4. Changes the products into different elements

Question 19

Combustion transfers energy in which direction?
  1. Reaction to surroundings
  2. Surroundings to reaction
  3. Products back to fuel
  4. Flame into new atoms

Question 20

Which conditions are needed for iron to rust?
  1. Oxygen and water
  2. Oxygen without water
  3. Water without oxygen
  4. Carbon dioxide and sunlight

Question 21

What happens to atoms during a chemical reaction?
  1. They rearrange into new combinations
  2. They are created from energy
  3. They disappear as reactants are used
  4. They change into different elements

Question 22

Which observation can indicate a chemical reaction?
  1. A temperature change
  2. A substance being cut
  3. Ice melting
  4. Water evaporating

Question 23

What forms when an acid reacts with a carbonate?
  1. Salt, water and carbon dioxide
  2. Salt and hydrogen
  3. Salt and oxygen
  4. Metal oxide and water

Question 24

Which pH range is acidic?
  1. Below 7
  2. Above 7
  3. Exactly 7
  4. Between 7 and 14

Question 25

Which pH range is alkaline?
  1. Above 7
  2. Below 7
  3. Exactly 7
  4. Between 0 and 7

Question 26

What forms when an acid reacts with a metal oxide?
  1. Salt and water
  2. Salt and hydrogen
  3. Metal and oxygen
  4. Alkali and carbon dioxide

Question 27

Which ion makes an aqueous solution acidic?
  1. Hydrogen ion, H+
  2. Hydroxide ion, OH−
  3. Sodium ion, Na+
  4. Chloride ion, Cl−

Question 28

What colour does universal indicator show for a strong alkali?
  1. Purple
  2. Red
  3. Orange
  4. Yellow

Question 29

Zinc displaces copper from copper sulfate. What does this show?
  1. Zinc is more reactive than copper
  2. Copper is more reactive than zinc
  3. Zinc and copper have equal reactivity
  4. Copper sulfate contains no copper

Question 30

Which is a physical change?
  1. Melting ice
  2. Burning wood
  3. Rusting iron
  4. Neutralising acid

About this topic

Review Chemical Reactions questions for Chemistry, with correct answers shown and coverage across what defines a chemical change; choosing which observation is good evidence that a chemical reaction has happened; choosing which equation is balanced for magnesium burning in oxygen.

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