Which of the following could be said about ecological footprints?
a. exact ecological footprints are often difficult to calculate, but estimates can be useful in comparing populations.
b. ecological footprints can't be used to determine carrying capacity.
c. ecological footprints don't take into account resources needed to absorb and manage wastes.
d. the average ecological footprints for various countries are nearly identical.

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

shield volcanos are angry and get mad over the smallest things so much that there heads erupt   pahoehoe and a'a lava. a composite volcano is the poller opposite of a shield volcano. its   peaceful thing and knows how to control its emotions.