Page 61 - Spotlight A+ Form 4 & 5 Chemistry KSSM

Chemistry Answer
2. (a) There are some empty spaces between atoms in the orderly
arrangement of atoms. When a metal is knocked, atoms of
Set of experiment 1 2 3 4 5 the same size slide into new positions to fill the empty of
space. Therefore, metals are malleable.
2. (a) Iron
Concentration of atom
Na S O solution 0.1(50) 0.1(40) 0.1(30) 0.1(20) 0.1(10)
50
50
50
50
50
3
2 2
that reacts, M 2 Carbon
(mol dm ) = 0.1 = 0.08 = 0.06 = 0.04 = 0.02 Pure iron atom
–3
Steel
1 (s ) (b) The presence of carbon atoms which are of different
–1
Time 0.05 = 0.1 0.03 0.02 0.01 sizes with iron atoms disrupt the orderly arrangement

of iron atoms. Layers of iron atoms become more
Table 2 difficult to slide over one another when force is applied.
3. (a) Copper, aluminium, magnesium,
(b) Graph of a gainst concentration of thiosulphate manganese (any two answers).
1
—
Time
1 (b) Light, hard, resistant to corrosion.
–1
— (s )
Time 4. (a) Pewter
(b) Zinc, copper
0.05 (c) Manufacture of musical instruments; Manufacture of
electrical parts
0.04
8.2
1. Silicon and oxygen
0.03
2. (a) Silica
(b) Soda-lime glass
0.02 (c) Silica, sodium carbonate, calcium carbonate, aluminium
oxide, boron oxide 15 × 2500 g
ANSWER FORM 4 ©PAN ASIA PUBLICATIONS
(d) Lead cystal glass

0.01
3. Mass of boron oxide =
100
= 375 g

4. Lead crystal glass. It has high refraction index and is able to
0.10
0.08
0.06
0.02
0.04
refract the light from the bulb to the surroundings to make the
lobby look brighter and more beautiful.
Concentration (mol dm )
–3
(c) When the concentration of sodium thiosulphate,
1
solution increases, the value of Time also increases. 8.3
(d) Yellow precipitate is formed. 1. Extremely hard and strong; Brittle and easily break;
(e) The higher the concentration of sodium thiosulphate Chemically inert; Opaque
solution, the shorter the time for the ‘X’ mark to 2. Silicon, oxygen, metal
disappear from sight. 3. Oxide, carbide, nitride
(f) Add distilled water to sodium thiosulphate solution to 4. (a) Have semiconducting properties and can store charges.
change the concentration of sodium thiosulphate. (b) Withstand thermal shock and higher heat resistance.
Use the same size of conical flask, same concentration
and volume of dilute sulphuric acid.
8.4
Chapter 8 Manufactured Substances in Industry 1. Substance made from a combination of two or more
non-homogeneous materials, namely matrix substance and
8.1 strengthening substance.
2. Optical fibre, fibre glass.
1. Ductility of metals:
3. The concrete is strong but brittle with low tensile strength.
Therefore, steel should be added in concrete to strengthen the
Force Layers of concrete and produce a composite material which is strong,
atoms slide
Force over one high tensile strength and high compression strength.
another 4. Silica glass fibre is a strengthening substance, glass or plastic
coating are matrix substances.
Equal size of atoms are orderly arranged. The layers of atoms 5. The condominium is prone to intense sunlight. Photochromic
can slide over one another when a force is applied. Therefore, glass can turn dark when exposed to light. As the sun becomes
metals are ductile. brighter, the photochromic glass becomes darker. So, the space
Malleability of metals: inside the condominium is neither too bright nor too hot.
When cloudy, the photochromic glass becomes transparent. The
condition inside the condominium is not dark and does not
Force The shape
of the metal need to switch on the light.
changes
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