Answer:
substance A is water and substance B is chlorophyll
Explanation:
<span>The number of molecules of each gas must be equal since 1 mol of any gas needs to contain 6.02x10^23 molecules. So 1mol O</span>₂ and 1mol CO both need to contain 6.02x10^23 molecules
False.
Na does represent sodium, but NOT when it lost an electron. Na+ represents sdoium when it lost its electron.
Answer:- 0.00724 moles.
Solution:- Grams of salicylic acid are given and it asks to calculate the moles.
For the moles, we divide the grams by the molar mass.
Formula of salicylic acid is 
Molar mass = 7(12.01)+6(1.01)+3(16.00)
= 84.07+6.06+48.00
= 138.13 gram per mol
We could make the dimensional analysis set up for showing unit cancellation and have the moles.

= 0.00724 moles
So, there will be 0.00724 moles of salicylic acid in it's 1.00 gram.
Answer: Aluminium
Explanation: Aluminium metal has a lower density than copper. So, for the same volume of metal used to build a model airplane, the aluminium plane would be very lightweight while that of copper would be heavy. The lightweight airplane will fly easily.