Consider the following statements, and then rate them using the following scale: 1 = strongly agree 2 = undecided 3 = strongly disagree

a. Plastic goods are essential in our modern world:
b. Plastics do not harm the environment if we recycle them:
c. We need to invent more biodegradable plastics:
d. Plastic products are better than products made of glass, metal or paper because plastic costs less:
e. Chemicals fertilizers and pesticides endanger young children and animals:
f. Chemicals do not harm the soil, even if they are harmful to pests:

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.