Page 57 - Spotlight A+ Form 4 & 5 Chemistry KSSM

ANSWERS Complete Answers
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Form 4 (b) (i) Vinegar; salt; baking powder

(ii) Vinegar: preserves food
Salt: gives salty taste
Chapter 1 Introduction to Chemistry Baking powder: raises the dough
(c) Chemist; doctor
1.1 (d) Hydrogen peroxide waste with low concentration
6. B ©PAN ASIA PUBLICATIONS
can be poured directly into the sink. Concentrated
1. A field of science that studies the structures, properties, hydrogen peroxide wastes need to be diluted with
compositions and interactions between matter. water. Then, it is added with sodium sulphite for the
2. Herbicide; Hormone purpose of decomposition before being poured into the
3. With nanotechnology, sunscreens are no longer oily sink.
nowadays and are colourless when applied to the skin. 2. (a) (i) Presence of water and oxygen
4. (a) Cosmetic consultant (ii) Rusting of iron nail
(b) Dietitian (iii) Type of nail
(c) Pathologist (b) Water and oxygen are needed for iron rusting.
(d) Veterinarian (c)
Test tube Observation
1.2 A Iron nail does not rust.
1. A systematic scientific method used to solve science related B Iron nail rusts.
problems. C Iron nail does not rust.
2. (a) When the temperature increases, the mass of salt
dissolved also increases. (d) Oxygen and water must be present for the iron nail to
(b) Manipulated variable: Temperature rust.
Responding variable: Mass of salt dissolved
Section B
3. (a) The scientific method is a systematic approach to solve
1.3 problems in science. ANSWER FORM 4
1. • Do not eat, drink, chase or run in the laboratory. (b) Making an observation
• Do not pour the chemicals back to the reagent bottles.
2. • Keep flammable substances away from the heat source. Making an inference
• Do not point the mouth of the test tube at your face or
at other people.
3. (a) To carry out experiment that involves the release of Identifying the problem
toxic vapours, gases that can cause combustion or gases
with pungent smell. Making a hypothesis
(b) To remove dirt, oil, chemicals or microorganisms from
the hands. Identifying the variables
(c) To wash and clean the body if accident happens on
parts of the body. It is also used to put out fire at any Controlling the variables
part of the body if there is fire.
4. (a) Kept in paraffin oil to prevent reaction between this Planning an experiment
chemical with moisture, water and air.
(b) Kept in dark bottles to avoid the exposure of sunlight.
5. Mercury poisoning is a phenomenon when a person is Collecting data
exposed to mercury in a certain amount. Two symptoms of
mercury poisoning are vomiting and difficult in breathing. Interpreting data
Making a conclusion

Paper 1 Writing a report
1. A 2. A 3. C 4. B 5. C
7. B 8. D 9. B 10. C Section C
11. B 12. C 13. A 14. C 15. D
4. (a) (i) Ammonium nitrate / Urea
(ii) Occupation A: Pharmacist
Paper 2 Occupation B: Pathologist
Section A (b) • Inform the accident to the teacher immediately.
1. (a) Chemistry is defined as a field of science that • Make the spill area as a restricted area for students.
studies the structures, properties, compositions and • Try to stop the spill from spreading to other areas
interactions between matter. using sand to border it.
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