A Level Chemistry
CIE A Level Chemistry (9701) Solved Past Paper May/June 2019 P21

CIE A Level Chemistry (9701) Solved Past Paper May/June 2019 P21

1 ai) Removal of electrons is about ionisation energy, atoms (like Mg in this Q) which have their outermost shell electrons nearer to nucleus are highly attracted to its nucleus and thus require greater energy to remove the electrons.

ii) Group II elements + water——–> Group II hydroxides + hydrogen

iii) Group II hydroxides are more soluble down the group and group II sulfates are more soluble on the top.

b) Group II oxides are white in colour

2 di) Atom with higher electronegativity value in a bond gets partial negative and that of lower electronegativity gets a partial positive charge.

3b) Argon is a noble with complete outermost shell, its first 8 successive ionisation energies must be almost the same since the electrons are from the same shell but there is going to be a huge difference between its 8th and 9th ionisation energies because of the difference in the shell. Its 9th electron is in the shell which is closer to nucleus as compared to that of 8th electron which means that there is going to be stronger force of attraction (nucleur force) between 9th electron being taken out and its nucleus.

4a) Numbering of the longest carbon chain should start from the side which gives least number to the functional group (i.e C=C in this Q).

cii) There is a gain of 2 oxygen atoms which is Oxidation

iii) The first Carbon atom from the right is attached to -OH group along with 2 Hydrogen atoms which shows that a Primary alcohol is present and the middle Carbon atom is attached to only 1 Hydrogen atom and -OH group which shows that a secondary alcohol is present too in the structure. #

dii) Tollen’s reagent is specifically used to identify if an aldehyde is present in the solution, if it is then the mixture turns silver. Alkaline iodine is used to identify secondary alcohols, ketones and ethanal, if any of these three is present then yellow precipitate forms (i.e Tri-iodomethane).

5 a) H-CN bond breaks hetrolytically with CN taking away both the electrons which were being shared to form the covalent bond and now carrying a lone pair of electrons with a negative charge while Hydrogen has a positive charge.

c) Dilute sulfuric & hydrochloric acid are the reagents which convert nitrile group to carboxylic acid.

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