Which of the metals would reduce an iron ion
F
Fe
Cr
Cu
Ag
Sn

Cu

Explanation:

Copper since it is more reactive than Iron. Hence, it can easily displace ions in an iron based compound.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.