Biology ! ( 40 pts ) and you!

which of the following elements would be the most reactive?

strontium
nitrogen
chlorine
radon

name an element which will chemically behave like xenon.

iodine
carbon
neon
plutonium

how many electrons does a neutral atom of calcium (ca) possess?

none
five
twenty
fourty

what are the starting chemicals in a reaction called?

the products
the reactants
the equilibrium
the yield

what would be a representation of a single-replacement reaction?

a + b --> ab
ab --> a + b
ab + c --> ac + b
ab + cd --> ad + cb

Apart of an ecosystem that can restrict the growth of a population is referred to as

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area

Long term exposure to waves can cause sunburns and skin cancer.