Daily Practice

GCSE Science

28th July 1990

5 questions · GCSE · 584 questions in this band

1
Chemical Changes
A student reacts 2.4 g of magnesium with excess dilute hydrochloric acid: Mg + 2HCl -> MgCl2 + H2. Relative atomic mass of Mg = 24. Calculate the number of moles of hydrogen gas produced.
2
Reactivity, Acids and Salts
Why is aluminium extracted by electrolysis rather than by reduction with carbon?
3
Electrolysis
Concentrated sodium chloride solution (brine) is electrolysed using inert electrodes. State the products formed at the cathode and at the anode.
4
Energy Changes
A reaction profile shows the reactants at 220 kJ and the products at 340 kJ. State whether the reaction is exothermic or endothermic.
5
Exothermic and Endothermic Reactions
Explain, in terms of the reaction pathway, why adding a catalyst increases the rate of a reaction without changing the overall energy change of the reaction.

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