Answer:
An Element
Explanation:
An Element is made up of only one type of atom (Gold, Silver, etc.)
Hope this helps!
Answer: D and A
Explanation: <u>D</u> cuz you need water to have good soil and <u>A</u> cuz you get better soil if its warm. (: ( 'u' ) ( 'U' )
<u>Answer:</u> From the given gases, the greatest rate of effusion is of 
<u>Explanation:</u>
Rate of effusion of a gas is determined by a law known as Graham's Law.
This law states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows:

It is visible that molar mass is inversely related to rate of effusion. So, the gas having lowest molar mass will have the highest rate of effusion.
For the given gases:
Molar mass of 
Molar mass of 
Molar mass of 
Molar mass of 
Molar mass of 
The molar mass of methane gas is the lowest. Thus, it will have the greatest rate of effusion.
Hence, the greatest rate of effusion is of 
Answer:
A. Water
Explanation:
The formula for photosynthesis is carbon dioxide plus water which (with sunlight and chlorophyll) gets converted into glucose + oxygen, energy for the plant.
Without water, photosynthesis is unable to properly take place and plants are unable to produce the energy needed for them to continue maintaining life.