Daily Practice

GCSE Science

19th May 1991

5 questions · GCSE · 584 questions in this band

1
Concentration, Yield and Atom Economy
State two reasons why a percentage yield is less than 100 percent.
2
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.
3
Reactivity, Acids and Salts
Complete: acid + metal carbonate gives ...
4
Electrolysis
In the industrial extraction of aluminium, explain why the carbon anodes need to be replaced regularly.
5
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.

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