2b. The positions of the amine and imine groups in relation to each other are similar for both histamine and antihistamine which allows the antihistamines to compete with the histamines.
4a. Manufacturers can put labels on their supplements, talking about its health claims (what happens when you take the supplement and other food or food components) , its nutrient contents (how much nutrients the supplement can give), and its structure, describing how a product may affect the organic or the body.
4b. Somewhat. The Health Sciences Authority controls the flow of Chinese Proprietary Medicine into Singapore by issuing licence and testing of drugs before they are sold to the market.
1) Styrofoam contains a lot of air pockets. When dissolved in acetone, the air pockets are released and only the resin is left. That is why it is “solid and much denser”, because the air pockets, which makes it less dense, are no longer there.
2a) LDPE is not strong enough and can be easily broken or cut
2b) Weak but extensive dispersion forces allow the molecules to slip past one another, allowing flexibility. The linear arrangement also allows for greater strength.
A plastic molecule.
3) Plastic molecules are aligned in the same direction when stretched. When the pulling continues, it is stretched beyond its ultimate tensile strength and the structure eventually breaks. Paper, however, is brittle. The rigid cellulose molecules in paper are not able move around and change direction when stretched, hence they get torn and not stretched.
4a) Inert, durable, flexible, non-toxic
4b) Hard contact lenses are made of PMMA or poly(methacrylate). Soft contact lenses are made of HEMA, poly(hydroxyethyl methacrylate). Contact lenses need to have high oxygen permeability, refractive properties and hydrophilic. (Reference)
4c) Hard contact lens are easier to wear and clearer, but it is more uncomfortable. It is usually prescribed to astigmatism cases and to correct bi-focal problems. Soft contact lenses are more comfortable and stays in place better. Oxygen is allowed to pass through the contact lens to the cornea due to the flexibility of the soft contact lens when combined with water. (Reference)
1a) Coal-fired plants produce smog, which prevents visibility.
China is one of the countries in the world whose cities has been hit by smog almost everyday. Photo: The Verge
1b) Normal rainfall has a pH of 5-5.5 (see here), so a rainfall 10 times more acidic would mean that it has a pH of 4-4.5.
2a) You will use less electricity, therefore you create lesser demand for electricity, and therefore, power plants will generate lesser electricity. This will bring down the amount of SOx released into the atmosphere.
2b) The amount of nitrogen oxide produced by the automobiles will be reduced.
2c) Less electricity is being used, and the water would be cleaner and less polluted from chemicals arising from the detergents and other chemicals. Less resources also will be used to clean that “dirty water”.
2d) Reduce electricity to heat the water, by preventing heat loss.
2e) Reduces transportation. But this answer is not always true, as some plants that are required for subsistence may not be native. Therefore, greenhouses must be built, which requires massive amounts of energy creation.
Acid rain has devastating effects on the environment, among which is the acidification of freshwater lakes, which makes lakes it impossible for marine life to live there
– Cap the production of SO2 at 2.3 million tonnes in the seven Canadian easternmost regions, to be met from 1994 and maintained from 1994 to 2000.
– Work with the US government to reduce the flows of acid pollution from the US into Canada
– Signed the US-Canada Air Quality Agreement of 1991, which led to the monitoring of emissions, reduction of sulphur and nitrogen oxide emissions
In Singapore, we generally do not have acid rain. However, haze (air pollution) is a major problem in Singapore. Haze is created by the mass burning of forests in Indonesia. This is usually done at the start of the farming season, when Farmers burn the land to make the soil more fertile for the next batch of crops. Haze disrupts daily activities, reduces visibility and aggravates health issues for those who are particularly susceptible to air pollution.
1) Chlorine tablets, distillation and filtration. In terms of cost, a good filter bottle or straw may be more costly as compared to distillation and the chlorine tablets. Chlorine tablets can be easily bought from convenience stores and distillation can be easily done using a portable stove and a messtin. In terms of effectiveness, a good filter may be the best option to purify water as it is able to filter out bigger unwanted particles and kill bacteria. However, it needs to be regularly replaced. Using all three methods will be the most effective in killing pathogenic bacteria and purifying water.
Similar methods used in purifying municiple water supplies are chlorination, distillation and filtration.
2) Desalination is more costly and energy intensive. It is usually done by energy rich countries.
3)
a) Corroded water pipes or pipe soldering using lead.
b) It is possible if irresposible acts lead to lead leakage into the drinking water pipes. However in most cases, the drinking water pipes are not connected to the water drainage system.
4) Water soluble vitamins are polar. They are able to form hydrogen bonds with water molecules.
Fat soluble vitamins are non-polar. They are hydrophobic and dissolve in other non-polar substances.
The greenhouse gases trap some of the heat and retains it in the atmosphere. The increase in greenhouse gases because of pollution activities naturally causes this rise. Also, as ice melts into water, the ocean water tends to trap the heat more rather than reflecting it as ice.
The statement “lowered my concerns” is incorrect. Global warming affects different part of the world differently; colder places get colder and warmer places, warmer. Hence it is wrong to attribute the presence of more snow to a lack of global warming. Further, the term “global warming” might be misleading, as it gives an impression of rising temperatures across the world; the term “climate change” should be used instead, as global warming affects different countries differently.
It was unsuccessful because blasting microwave radiation at water molecules only causes the water molecules to rotate faster and generate more heat and IR radiation, instead of transmitting the signals back.
In the short run, the air quality affects us the most, because we need to breathe in air. Further, the diseases that come about as a result of bad air quality lasts a whole lifetime, which makes it even worse. In the long run, global warming will affect us the most because it involves habitats, our food production and also the way we live as human beings.
a) Exothermic. Requires energy to start the combustion.
b) Endothermic. Heat from the skin transfers to water on the skin. Heat is converted into kinetic energy i.e. gas molecules are moving.
c) Endothermic. Heat is added causing the molecules to move, increasing kinetic energy.
2. For the reactants the bond strength would be weaker because less energy is required to break the bond. For the products the bond strength would be stronger resulted in more energy being released.
3. Heat is the flow of energy from hotter to colder objects. Temperature determines direction of heat flow. To give an example, the number of people in a room. Each one of us gives off heat transferring to the molecules in a room. The heat causes the molecules’ average speed to increase. Hence the rising temperature; the more people in a room, the higher the temperature.
4.
a) It has a knocking characteristics of 98% isooctane & 2% n-heptane.
b) No, we are not able to tell if it contains oxygenates.
