Substances have different tendencies to donate or accept electrons. When a really good donor meets a great acceptor, the chemical reaction releases a lot of energy. Oxygen (O2) is the best electron acceptor and is used in many aerobic reactions (reactions with oxygen). Hydrogen gas (H2) is a good electron donor.
When O2 and H2 are combined, along with a catalyst, water (H2O) is formed. This example of a redox reaction can be written like this:

3( 2 carbons + 4 hydrogen's + 2 oxygens)
3*(8) = 24
Yes because some work harder than others to get their credit for developing the periodic table
Answer:
5: 0.16
6: 50
Explanation:
Question 5:
We can use the equation density = mass/ volume.
We already have the mass (12g), but now we need to find the volume of the cylinder.
The equation for this is πr²h
So we know the radius is 2 and the height is 6.
π x (2)² x 6 = 24π = 75.398cm³
Now we can use the density equation above:
12/75.398 = 0.1592g/cm³ = 0.16g/cm³.
Question 6:
This time, we have to rearrange the equation density = mass/ volume to find the mass.
We know mass = density x volume.
From the question, the density is 2.5g/mL and the volume is 20mL.
Following the equation above, we do 2.5 x 20 to get 50g.
