Science: Middle School: Grades 6, 7 and 8 Quiz - Chemicals - Helpful and Harmful (Questions)

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Chemicals are substances found in a form of matter and can be helpful or harmful. That matter has constant chemical compositions and characteristic properties. The components of chemicals cannot be broken down without breaking down the chemical bonds. Chemicals are found in liquids, solids, gases and plasma.

Depending upon how they are controlled, handled and disposed of can make chemicals helpful or harmful. Over the past century, a large number of chemicals have been introduced into the environment. Some of the chemicals are released through industrial waste, including smoke that is released through chimneys.

Others have come through the field of medicine but, although they can be helpful, their disposal can have devastating effects upon the environment.

Below is a brief listing of some helpful chemicals and some harmful chemicals.

SOME HELPFUL CHEMICALS

Antibiotics (such as penicillin) - Helps to fight infections.
Sodium Chloride (table salt) - This is an important mineral that the body needs.
Cornstarch - This is made from ground corn and contains multivitamins.
Vinegar - For cuts and bruises, vinegar acts as an antiseptic.
Baking soda (sodium bicarbonate) - Reduces stomach acids that cause indigestion.

SOME HARMFUL CHEMICALS

You might be interested to learn that there are several harmful chemicals found in your everyday drinking water. The following is a list of the five most harmful chemicals in tap water.

Chlorine - Yes, chlorine that is found in swimming pools. Chlorine kills bacteria which is a good thing but for humans and animals, it dries out the skin and hair which can turn into other health issues.
Lead - One of the most dangerous chemicals that is found in drinking water is that of lead. Too much lead in the body can damage the nervous system, the kidneys and even the brain. Often the lead gets into the water from the pipes that the water flows through.
Pesticides - Pesticides are used greatly in agriculture to preserve vegetation. However, the pesticides work their way through the soil into the groundwater which then is used in tap water. The amount of pesticide, over time, can cause severe to chronic health problems in both humans and animals.
Benzene - This particular chemical is a known carcinogen that has been linked to leukemia. It is also an additive to gas to increase its octane. In addition, it can be found in the smoke of cigarettes.
Arsenic, Mercury and Cadmium - These are all heavy metals that have all been linked to cancer, damage to the nervous system and even death.