Note to self: Should you ever wish to point out the depreciation in examination standards in recent years, the poor show made by modern students with their modern, flashy GCSEs (not a patch on the traditional, solid, O-levels of years gone by), then please note the following:
You really, really don't help your argument by, oh yes, making multiple mistakes in your answer sheet.
Should you be interested:
A titration can be used to find the concentration of a solution. In a titration, 22.0 cm3 of hydrochloric acid is required to neutralise 25.0 cm3 of calcium hydroxide solution. The concentration of the hydrochloric acid is 0.001 mol/dm3.
The equation for the reaction is: Ca(OH)2 + 2HCl → CaCl2 + 2H2O
(Relative atomic masses: H = 1; O = 16; Ca = 40)
How many moles of hydrochloric acid are present in 22.0 cm3 of the acid solution? (Answer to 2 sig. fig.)
Given and correct answer: 2.2E-5 mol/dm3
With how many moles of calcium hydroxide will 22.0 cm3 of this acid solution react? (Answer to 2 sig. fig.)
Given and correct answer: 1.1E-5 mols
What is the concentration of the calcium hydroxide solution? (Answer in mol/dm3 to 2 sig. fig.)
Given and correct answer: 4.4E-4 mol/dm3
What is the concentration of the calcium hydroxide solution? (Answer in g/dm3 to 2 sig. fig.)
Given answer: 0.33 g/dm3
Correct answer: 0.033 g/dm3
Nitrogen can be obtained by heating solid ammonium dichromate(VI), (NH4)2Cr2O7. Chromium (III) oxide (Cr2O3) and steam are the only other products of this reaction.
(i) Construct the equation, including state symbols, for the action of heat on ammonium dichromate(VI).
Given answer: 2(NH4)2Cr2O7(s) --> 2Cr2O3(s) + H2O(g) + N2(g)
Correct answer: (NH4)2Cr2O7(s) --> Cr2O3(s) + 4H2O(g) + N2(g)
Their version doesn't even balance! We lose 2 N atoms, 14 H atoms, and 7 O atoms!!
One of the hydrocarbons in petrol is octane. This equation shows the combustion of octane: 2C8H18 + 25O2 → 16CO2 + 18H2O
What mass of carbon dioxide is produced for every tonne of octane burned in this reaction? (Relative atomic masses: H = 1; C = 12; O = 16) (Answer in tonnes to 2 sig. fig.)
Given answer: 3.1 tonnes
Correct answer: 3.4 tonnes
Basically, unimpressive. I got bored after Question B4, so there might be errors in the answers after that point too. I'll update this if I get that far.
You really, really don't help your argument by, oh yes, making multiple mistakes in your answer sheet.
Should you be interested:
A titration can be used to find the concentration of a solution. In a titration, 22.0 cm3 of hydrochloric acid is required to neutralise 25.0 cm3 of calcium hydroxide solution. The concentration of the hydrochloric acid is 0.001 mol/dm3.
The equation for the reaction is: Ca(OH)2 + 2HCl → CaCl2 + 2H2O
(Relative atomic masses: H = 1; O = 16; Ca = 40)
How many moles of hydrochloric acid are present in 22.0 cm3 of the acid solution? (Answer to 2 sig. fig.)
Given and correct answer: 2.2E-5 mol/dm3
With how many moles of calcium hydroxide will 22.0 cm3 of this acid solution react? (Answer to 2 sig. fig.)
Given and correct answer: 1.1E-5 mols
What is the concentration of the calcium hydroxide solution? (Answer in mol/dm3 to 2 sig. fig.)
Given and correct answer: 4.4E-4 mol/dm3
What is the concentration of the calcium hydroxide solution? (Answer in g/dm3 to 2 sig. fig.)
Given answer: 0.33 g/dm3
Correct answer: 0.033 g/dm3
Nitrogen can be obtained by heating solid ammonium dichromate(VI), (NH4)2Cr2O7. Chromium (III) oxide (Cr2O3) and steam are the only other products of this reaction.
(i) Construct the equation, including state symbols, for the action of heat on ammonium dichromate(VI).
Given answer: 2(NH4)2Cr2O7(s) --> 2Cr2O3(s) + H2O(g) + N2(g)
Correct answer: (NH4)2Cr2O7(s) --> Cr2O3(s) + 4H2O(g) + N2(g)
Their version doesn't even balance! We lose 2 N atoms, 14 H atoms, and 7 O atoms!!
One of the hydrocarbons in petrol is octane. This equation shows the combustion of octane: 2C8H18 + 25O2 → 16CO2 + 18H2O
What mass of carbon dioxide is produced for every tonne of octane burned in this reaction? (Relative atomic masses: H = 1; C = 12; O = 16) (Answer in tonnes to 2 sig. fig.)
Given answer: 3.1 tonnes
Correct answer: 3.4 tonnes
Basically, unimpressive. I got bored after Question B4, so there might be errors in the answers after that point too. I'll update this if I get that far.
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