Xinying (Paper 1)
Becca (Paper 1)
Kaixin
Chew Yen
Bao Xian
Huizhen
These answers will be removed on 13th Oct Tuesday
Paper 1
Qn | Ans | Qn | Ans | Qn | Ans | Qn | Ans | Qn | Ans |
1 | D | 2 | D | 3 | C | 4 | B | 5 | C |
6 | A | 7 | C | 8 | A | 9 | C | 10 | D |
11 | D | 12 | B | 13 | A | 14 | A | 15 | B |
16 | D | 17 | C | 18 | B | 19 | C | 20 | D |
21 | B | 22 | D | 23 | C | 24 | C | 25 | B |
26 | D | 27 | A | 28 | A | 29 | C | 30 | C |
31 | D | 32 | D | 33 | B | 34 | B | 35 | A |
36 | B | 37 | D | 38 | C | 39 | A | 40 | C |
No | Answer |
1a | - electronic balance - burette or pipette - stopwatch |
1bi | fixed boiling point of 100 °C |
1bii | 2H2O2 ® 2H2O + O2 |
1biii | - diagram showing clearly the filtration setup - residue labelled as powder and filtrate labelled as liquid |
1c | no as sodium chloride is dissolved in the water hence the water is impure |
1d | Human reaction time on the use of electronic stopwatch |
1e | effect of solid on the rate of gas production from hydrogen peroxide |
2ai | X : cannot be identified Y : vitamin D Z : vitamin K |
2aii | No as it contain a spot X which is not any of the known fat-soluble or water-soluble vitamins |
2b | To react and give a colour with the colourless spots so that they can be located |
2c | Only a small sample is required |
3a | - diagram shows 8 protons in nucleus - 10 neutrons in nucleus - 2 electrons in 1st shell, 6 electrons in 2nd shell |
3bi | 2 more neutrons (must specify the number) |
3bii | 16.1 (3 sf) |
3c | correct electronic structure of sodium ion (2,8) – 2 ions correct electronic structure of oxide ion (with 2 e- which is different) |
4ai | Ce2(SO4)3 – 37 g NaCl – 0 g KClO3 – 0 g |
4aii | 31 g |
4b | - add about 20 g of solid sample - to 100 g of water at 0°C - filter if necessary to remove any insoluble solid - heat up the solution to about 28°C |
5a | E |
5b | A and E or I and J |
5c | J |
5d | C or J with A, G or H |
5e | F |
5f | B or I |
No | Answer |
6a | - Group I as it has 1 valence electron - Period 4 as it has 4 shells of electrons |
6b | - roblium hydroxide - hydrogen gas |
6c | - no as it has ions - which are not mobile / held fixed in position at room conditions |
6d | - Ro2CO3 - AlIs3 |
7a | - water, H2O (both correct) - calcium sulfate, 20, 16, 8 (4) - PbI2, 82, 53(2) |
7b | no; as nucleon number are made of total number of protons and neutrons different elements, it is possible to have the same nucleon number |
7c | atoms : 4 elements : 2 |
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