You are interested in how different air temperatures affect the speed at which gas molecules move. With a classmate, you have planned the following investigation: Choose a very hot day in the classroom.

The students close all of the windows and doors in the classroom and turn off any fans.
The students measure the temperature in the classroom with a thermometer.
One student stands in the corner of the classroom with a stopwatch.
Another student, 10 meters away in the opposite corner of the room, opens a container filled with a safe, but strong-smelling gas.
The student with the stopwatch measures the amount of time before they can smell the gas.
Repeat the steps above on a very cold day in the classroom.
Identify the independent variable in this investigation from the list below:

A. The temperature of the room
B. Amount of time before they smell the gas
C. The distance between the two students in the room
D. Not enough information is provided to identify the independent variable
E. The type of gas in the container

It’s A, The temperature of the room.

Answerthis solution will not form a precipitateexplanationsolubility equilbrium:         pbf₂(s)  ⇄ pb²⁺(aq) + 2 f⁻(aq)the solubility product expression is    (we exclude solids from the equilibrium expression).now suppose we have the trial ion product q, which we can define as    then, we can interpret  q as the product of the concentration of the ions that we have and ksp as the product of the ion concentrations that are needed to form a saturated solution.if q > ksp, then that implies that there will be a surplus of ions that exceed the amount that is required to form a saturated solution. a precipitate will then form (the precipitate continually  forms until the surplus ions are removed and q is decreased to ksp's value).if q = ksp, the saturated solution that forms is barely saturated and the precipitate will be minimal.if q < ksp, then the ion concentration will not be enough to form a saturated solution (so no precipitate).using our information, we calculate the trial ion product:     since q = 2.7  × 10⁻⁸ < ksp =  4  ×  10⁻⁸, a precipitate will not form.