1 Compound B, shown below, is an antiviral medicine
i. What is the molecular formula of compound B
[1]
ii. How many chiral carbon atoms are there in one molecule of compound B?
[1]
iii. A research chemist synthesises two related compounds, compound C and compound D, from compound B.
• In compound C, the N atoms in compound B had been replaced by P atoms.
• In compound D, the O atoms in compound B had been replaced by S atoms.
What is the difference between the relative molecular masses of compound C and compound D?
difference = ................................................... [2]
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, 2 α-Amino acids have the general formula RCH(NH2)COOH.
The R group in an α-amino acid contains C and H only.
This R group has a molar mass of 91 g mol–1.
A polymer is formed from 500 molecules of this α-amino acid.
Determine the molar mass of this polymer.
Give your answer to the nearest whole number.
molar mass of polymer = .............................................. g mol–1 [3]
3 1.35 g of ethylamine gas, CH3CH2NH2 (Mr = 45.0), is reacted with 20 cm3 of 2.0 mol dm–3 hydrochloric acid
forming a solution of ethylammonium chloride.
CH3CH2NH2(g) + HCl(aq) → CH3CH2NH3+(aq) + Cl–(aq)
What is the concentration of ethylammonium chloride in mol dm–3?
A 0.03
B 0.67
C 1.50
D 2.00
Your answer [1]
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, 4 This question is about iron.
A sample of iron is isolated from a meteorite and analysed by mass spectrometry.
The mass spectrum shows peaks with the relative abundances below.
54 56 57 58
Isotope Fe Fe Fe Fe
Relative abundance 78.54% 8.88% 5.10% 7.48%
Calculate the relative atomic mass of the iron in the sample.
Give your answer to 2 decimal places.
relative atomic mass = ......................................................... [2]
5 Which row shows the atomic structure of 25Mg2+?
Protons Neutrons Electrons
A 10 12 13
B 10 15 12
C 12 13 10
D 12 13 14
Your answer [1]
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, 6 This question is about periodicity and the reaction of some Group 2 metals.
Periodicity is the repeating trend in properties of elements across different periods in the periodic table.
i. Complete the table below with the electron configurations and blocks.
Group 2 Group 17 (7)
Period 2 Be F
1s2 ........................................................ 1s2 ........................................................
Period 3 Mg Cl
1s2 ........................................................ 1s2 ........................................................
Block ............................. .............................
[3]
ii. Use your answers to (i) to explain why electron configuration is an example of a periodic trend.
[2]
iii. Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why.
[2]
iv. Magnesium reacts with oxygen in the air.
Write the equation for this reaction.
[1]
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i. What is the molecular formula of compound B
[1]
ii. How many chiral carbon atoms are there in one molecule of compound B?
[1]
iii. A research chemist synthesises two related compounds, compound C and compound D, from compound B.
• In compound C, the N atoms in compound B had been replaced by P atoms.
• In compound D, the O atoms in compound B had been replaced by S atoms.
What is the difference between the relative molecular masses of compound C and compound D?
difference = ................................................... [2]
© OCR 2025. You may photocopy this page. 1 of 68 Created in ExamBuilder
, 2 α-Amino acids have the general formula RCH(NH2)COOH.
The R group in an α-amino acid contains C and H only.
This R group has a molar mass of 91 g mol–1.
A polymer is formed from 500 molecules of this α-amino acid.
Determine the molar mass of this polymer.
Give your answer to the nearest whole number.
molar mass of polymer = .............................................. g mol–1 [3]
3 1.35 g of ethylamine gas, CH3CH2NH2 (Mr = 45.0), is reacted with 20 cm3 of 2.0 mol dm–3 hydrochloric acid
forming a solution of ethylammonium chloride.
CH3CH2NH2(g) + HCl(aq) → CH3CH2NH3+(aq) + Cl–(aq)
What is the concentration of ethylammonium chloride in mol dm–3?
A 0.03
B 0.67
C 1.50
D 2.00
Your answer [1]
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, 4 This question is about iron.
A sample of iron is isolated from a meteorite and analysed by mass spectrometry.
The mass spectrum shows peaks with the relative abundances below.
54 56 57 58
Isotope Fe Fe Fe Fe
Relative abundance 78.54% 8.88% 5.10% 7.48%
Calculate the relative atomic mass of the iron in the sample.
Give your answer to 2 decimal places.
relative atomic mass = ......................................................... [2]
5 Which row shows the atomic structure of 25Mg2+?
Protons Neutrons Electrons
A 10 12 13
B 10 15 12
C 12 13 10
D 12 13 14
Your answer [1]
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, 6 This question is about periodicity and the reaction of some Group 2 metals.
Periodicity is the repeating trend in properties of elements across different periods in the periodic table.
i. Complete the table below with the electron configurations and blocks.
Group 2 Group 17 (7)
Period 2 Be F
1s2 ........................................................ 1s2 ........................................................
Period 3 Mg Cl
1s2 ........................................................ 1s2 ........................................................
Block ............................. .............................
[3]
ii. Use your answers to (i) to explain why electron configuration is an example of a periodic trend.
[2]
iii. Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why.
[2]
iv. Magnesium reacts with oxygen in the air.
Write the equation for this reaction.
[1]
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