OCR Gateway GCSE Chemistry A Chemical reactions (C3) overview quiz quiz

Only the small subscript numbers written inside a formula

The big numbers in front of the formulae only

Both the small subscripts and the formulae themselves

Nothing at all, because equations always balance themselves

Extra mass is simply created out of nothing during the reaction itself

The magnesium loses electrons and this somehow makes it heavier overall

The hot crucible itself adds some of its own mass to the sample

The magnesium reacts with oxygen from the air, which adds to its mass

0.1 mol

10 mol

1000 mol

0.01 mol

125 percent

80 percent

6 percent

54 percent

Breaking bonds releases energy and making bonds takes in energy

Both release energy

Breaking bonds takes in energy and making bonds releases energy

Neither involves energy

A salt and hydrogen gas only, nothing else

Just a salt and water and nothing more

Only a salt is formed, with no other product

A salt, water and carbon dioxide

It is fully ionised, so it has a higher hydrogen ion concentration

It is always far more concentrated than the weaker acid is

It simply contains a much larger amount of water than the weak acid

It is only partially ionised, releasing fewer hydrogen ions overall

The gain of electrons

The loss of electrons

The gain of oxygen

The loss of protons

To the anode, where they lose electrons

To the cathode, where they lose electrons

To the cathode, where they gain electrons

They do not move

Electrolysis is always the cheapest possible way to extract aluminium

There is simply no naturally occurring ore that contains any aluminium

Carbon is more reactive than aluminium, so it readily displaces it

Aluminium is more reactive than carbon, so carbon cannot reduce it