Self assessment
Question 1 of 5
Which of the following statements about reactants and products in a chemical reaction are true?
A
They contain the same number of atoms.
B
The atoms are arranged in the same way.
C
They have the same mass.
D
They have the same energy.
Which of the following changes can be easily reversed?
A
Melting candle wax.
B
Burning magnesium ribbon.
C
Setting concrete.
D
Heating hydrated copper(II) sulfate crystals.
Which of the following changes may be classified as a physical rather than a chemical change?
A
Boiling ethanol.
B
Burning wood.
C
Adding magnesium ribbon to hydrochloric acid.
D
Freezing water.
Which of the following will turn anhydrous copper(II) sulfate from white to blue?
A
Ethanol.
B
Cooking oil.
C
Sodium chloride solution.
D
Water.
The enthalpy change for the decomposition of calcium carbonate is +178 kJ mol–1. What will be the enthalpy change for the reverse reaction in which calcium carbonate is made from calcium oxide and carbon dioxide?
A
+356 kJ mol–1
B
+178 kJ mol–1
C
–178 kJ mol–1
D
–89 kJ mol–1