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Looking at the information given in the description, the experiment is testing for the effects of the different salts on the growth of the plants.
This means that the type of salt is the independent variable, or the variable being manipulated and tested.
To ensure fair results, some parts of the experiment would need to be kept the same, which is the control. The only answer choice that makes sense in this instance is A. water.
Answer:
<em>molar mass of the phosphorus chloride = 138.06 g/mol</em>
<em></em>
Explanation:
<em>mass of phosphorus will be the same as mass of CO2, since it is stated that they are of equal amount.</em>
mass = 3.51 g
<em>lets assume that it took the CO2 1 sec to effuse, then the time taken by the phosphorus chloride will be 1.77 sec</em>
From this we can say that
rate of effusion of CO2 = 3.51/1 = 3.51 g/s
rate of effusion of the phosphorus chloride = 3.51/1.77 = 1.98 g/s
<em>From graham's equation of effusion</em>,
=
Rc = rate of effusion of CO2 = 3.51 g/s
Rp = rate of effusion of phosphorus chloride = 1.98 g/s
Mc = molar mass of CO2 = 44.01 g/mol
Mp = molar mass of the phosphorus chloride = ?
Imputing values into the equation, we have
=
1.77 =
11.75 =
Mp =
Mp = <em>molar mass of the phosphorus chloride = 138.06 g/mol</em>