This should help
1 kPa = 1000 pascals (Pa)
1 mmHg = 133.322 pascals (Pa)
kPa value x 1000 Pa = mmHg value x 133.322 Pa.
kPa value = mmHg value x 0.133322
5.512 litres is the volume of 15.2 grams of sulphur dioxide gas at STP.
Explanation:
Data given:
mass of sulphur dioxide = 15.2 grams
conditions is at STP whech means volume = 22.4 litres
atomic mass of sulphur dioxide = 64.06 grams/mole
Number of moles is calculated as:
number of moles = 
Putting the values in the equation:
number of moles = 
= 0.23 moles
Assuming that sulphur dioxide behaves as an ideal gas, we can calculate the volume as:
When 1 mole of sulphur dioxide occupies 22.4 litres at STP
Then 0.23 moles of sulphur dioxide occupies 22.4 x 0.23
= 5.152 litres is the volume.
If H+ would have to dissociate from a substance and must be the only positive ion in the solution that substance must be an acid.
CH3CHO is an aldehyde called acetaldehyde.
CH3CH2OH is an alcohol called ethanol
CH3OCH3 is an ether called dimethyl ether.
and finally, the answer CH3COOH is a weak acid called acetic acid.
Sorry this will probably be pretty long.
So think of the "control" as being something you yourself add to increase or decrease the effects in an experiment.
I'll give you an example so it is not as confusing.
Say you have decided to make an experiment on plants. Which plant can grow the fastest on which type of liquid? What is being added to this experiment? The liquid! Or all of the liquids you used. Like if you used Coke, Lime Gatorade, Orange Gatorade, and Water. Each drink will EFFECT each plant differently.
Hope I was of any hope?