Daily Practice

GCSE Science

15th May 1977

5 questions · GCSE · 584 questions in this band

1
Moles, Formulae and Equations
Calculate the mass of 0.25 mol of sodium hydroxide, NaOH. (Na = 23, O = 16, H = 1)
2
Concentration, Yield and Atom Economy
Give the formula for atom economy.
3
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.
4
Reactivity, Acids and Salts
Why is aluminium extracted by electrolysis rather than by reduction with carbon?
5
Electrolysis
In the industrial extraction of aluminium, explain why the carbon anodes need to be replaced regularly.

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