33

Group 33 Group Name : 33
Group Members :
NG PEI LING, MAGDALENA SI HOE SIAN MIN, ONG KEYUAN, DERRICK KOH JUN MING, GOH HUAN RONG BERNICE, TANG PEI HUI BENJAMIN
1.

As they are clones, they will have identical DNA with the original, hence defects will also be carried over due to the lack of genetic diversity
They also will not have a long lifespan.

2.

GMO is fast growing, has more nutrients and is more resistant to pests and harsher climates, hence likely to grow better and alleviate the problem.

The long term effect of GMO foods on the human body (e.g. allergies) has not been determined.
Pests in the country will become more resistant against pesticides in the long term and wild corn might be further threatened. They will also threaten the natural balance if they spread to the wild.

Political costs will have to be considered given the opinions the general populace have on GMO.

3.
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Group 33

Group 33 Group Name : Group 33
Group Members :
Ong Keyuan. Magdalena Si Hoe, Goh Huan Rong Bernice, Ng Pei Ling, Derrick Koh, Benjamin Tang
1.

a) Cn(H2O)n
b) Glucose (written on paper)
c) It will be different. Different isomers of fructose will take different times to bind with the sweetness receptors on the tongue due to the different chemical structure affecting its “fit” with the receptor

2.

“All Organic” – not possible as we will need minerals like Cl, Zn, Ca which are inorganic
“Chemical – free” – not possible as everything that we consume is composed of chemicals, even so, most of the food and water in modern society have been chemically treated. There is also no need to go on a chemical free diet.

3.
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10.
[361]

Group 33

Group 33 Group Name : Group 33
Group Members :
Ong Keyuan. Magdalena Si Hoe, Goh Huan Rong Bernice, Ng Pei Ling, Derrick Koh, Benjamin Tang
1.

The acetone results in the dissolution of the polymer, allowing the gas of the foaming agent to escape. This results in the polymer collapsing on itself and becoming more dense as a result of the escaped gas.

2.

a. LDPE cannot be used because it is not strong enough
b. The molecules of HDPE must line up in a way that produces the required strength. Using a thin liner of HDPE allows sufficient flexibility

3.

When plastic is stretched, it results in the the polymers becoming aligned to each other in the direction of the pull. This change in structure is irreversible and will remain. However, when paper is pulled apart, it will tear because the polymers that paper is made of is not as flexible.

4.

a. Insoluble in body fluids, unreactive with body fluids, stable (non-biodegradable) , non-toxic

b, Hard lenses are made of polymethyl methacrylate. Softer contact lenses are made of silicone and more recently, newer rigid gas permeable (RGP) polymers contain fluorine: fluoro-silicone-acrylate polymers and fluoro-silicones.

c.The differences between the materials are their flexibility and oxygen permeability, hence the soft lenses are more comfortable.

5.
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6.
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7.
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8.
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9.
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10.
[311]

Group 33

Group 33 Group Name : Group 33
Group Members :
Derrick Koh Jun Ming, Magdalena Si Hoe Sian Min, Ng Pei Ling, Ong Keyuan, Goh Huan Rong Bernice, Tang Pei Hui Benjamin
1.

Carbon atoms differ in terms of:
1. The number of neutrons (For example, C-12, C-13)
2. The number of electrons (The atoms would form ions)

While all carbon atoms differ from all uranium atoms in terms of:
1. The number of protons (Uranium has 92 protons while Carbon has 6 protons)
2. The number of neutrons
3. The number of electrons
2. Chemical properties (For example, electronegativity)

2.

Symbol N represents nitrogen and stands for the naturally occurring mixture of all isotopes.
Symbol 14N and 15N represent specific isotopes with mass number of 14 and 15 respectively.

3.

a. There are 94 protons in the isotope.

b. Neptunium has 93 protons and Plutonium has 94 protons.

c. Radon-222 has 86 protons. Isotopes only differ in mass number but not proton number.

4.

A: Control rods
B: Cooling water out of the core
C: Control rod assembly
D: Cooling water into the core
E: Fuel rods

5.
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10.
[286]

Group 33

Group 33 Group Name : Group 33
Group Members :
Magdalena Si Hoe, Tang Hui Pei Benjamin, Derrick Koh Jun Ming, Goh Huan Rong, Ng Pei Ling, Ong Ke Yuan
1.

The techniques used for the desalination of water is distillation and reverse osmosis. However, both require a lot of energy in the process. For instance, reverse osmosis utilizes high pressure to push water molecules through a semipermeable membrane from a region of low water concentration to high water concentration. Therefore, the processes are very costly.

The processes are also impractical for large scale desalination. Greenhouse gases are emitted in the process, causing the processes not to be environmentally sustainable. The large energy consumption requirement also makes large scale production difficult.

2.

Solubility follows the rule “like dissolves like”.

Therefore, polar compounds will be soluble in polar solvents such was water, while non-polar compounds will be soluble in non-polar solvents like fat.

Vitamins that are water-soluble are polar whereas vitamins that are fat-soluble are non-polar.

3.

(a) Using the dryer to dry your clothes uses electricity and produces acid rain.

(b) Driving a car will result in vehicle exhaust that produces more Sox and Nox.

(c) This reduces the number of times we need to run the washing machine to clean all the dishes, reducing acid rain.

(d) Insulated hot water heaters and pipes are able to keep the water for a longer time, reducing electricity consumption and reducing acid rain.

4.

(a) Coal-fired plants release huge amounts of water vapour. When water vapour cools down, it becomes visible as fog, resulting in poor visibility for everyone.

(b)

Natural pH = 7
Acidic level is 10 times stronger than normal, pH level drops by 1
pH of rainfall =6

5.
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7.
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8.
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9.
[259]
10.
[261]

Group 33

Group 33 Group Name : Group 33
Group Members :
Goh Huan Rong Bernice, Ng Pei Ling, Magdalena Si Hoe, Derrick Koh Jun Ming, Ong Keyuan, Benjamin Tang Pei Hui
1.

a) Exothermic – the charcoal burns the skin and gives out heat

b) Endothermic – the skin feels cooler when water (like sweat) evaporates from the skin

c) Endothermic – the ice takes in heat to become water, which is an endothermic process

2.

The reactants should have very weak bonds and the products should have very strong bonds. The greater the energy difference between the products and reactants, the more vigorous the reaction as more energy is released.

3.

Heat is the transfer of energy from a hotter object to a cooler object, while temperature is the absolute amount of energy possessed by the object.

For example, heat is the steam given off by a cooking pot, which can cook an egg, but temperature is a measurement of how hot the steam is.

4.

a) An octane rating of 98 means that the gasoline has a knocking characteristic of 98% isooctane and 2% heptane. Isooctane has a lower boiling point than heptane and has a lower tendency to cause “knocking” in the engine. Therefore, gasoline with an octane rating of 98 would suggest a low tendency to cause knocking, and burns more smoothly.

b) The octane rating gives no clear indication of whether the fuel contains oxygenates. Examples of oxygenates include, MTBE, ETBE, methanol and ethanol. However, oxygenates enhance the octane number of the gasoline, assists combustion, reduces CO emissions and reduces knocking. Therefore, a high octane rating of 98 suggests that the gasoline does contain oxygenates, producing premium gasoline.

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