I think it's Potassium iodide because it has the highest solubility at 25°C.
I believe the answer is C because the first two are mechanical hazards and C mentions plug which is electrical.
Water is made of only one molecule which can be chemically separated into hydrogen and oxygen. The answer is D.
<h2>Answer:</h2><h3>The temperature of the gas: V</h3>
The temperature of gas is a variable quantity. It can be changed by changing energy or pressure of gas.
<h3>The amount of gas in the tube (in terms of mass and moles): C</h3>
It is a constant entity. As mass of gas once taken can not be changed by changing temperature, pressure etc.
<h3>The radius of the tube: C</h3>
The radius of tube cannot change at any rate.
<h3>The temperature of the gas (changed by the water surrounding it): V</h3>
It can be changed by changing the temperature of water surrounding it.
<h3>The type of gas: C</h3>
It can never be changed.
<h3>The pressure of the gas: V</h3>
It can be changed by simply changing temperature and volume of gas.