Sample Response: The properties of plastics make them useful in making products that are beneficial to society. Plastics and their production are costly, and are harmful to the environment, to humans, and to many other organisms.
There are both advantages and disadvantages in using plastics: The advantages are: Plastic is cheap to manufacture because it is easy to mold. It is light but durable and unbreakable. Plastic does not rust and it is water resistant. Plastic is reusable over and over again and when it is worn, the cost of replacement is cheaper than glass or rubber. It is odorless and chemical resistant. The disadvantages of plastic are: Plastic can cause cancer. Recycling plastic can cause toxic chemicals to be released during the process. It has low heat resistance and melts when placed near fires. Plastic containers for food absorb the smell of the food even when washed thoroughly. Small parts in plastic toys can cause choking in small children, the same with plastic bags when accidentally wrapped around children's heads. Plastics can clog up sewer systems when people through them away indiscriminately.
The density of the aluminium was calculated by a human and this is not natural but can be due to errors in the calibration of the scale for measuring the weight or taking readings from the measuring cylinder.
Random errors are natural errors. Random errors in experimental measurements are caused by unknown and unpredictable changes in the experiment. Systematic errors are due to imprecision or problems with instruments.
