The absolute value of the difference in electronegativity (ΔEN) of two bonded atoms provides a rough measure of the polarity to be expected in the bond and, thus, the bond type. When the difference is very small or zero, the bond is covalent and nonpolar. When it is large, the bond is polar covalent or ionic.
Answer: Option (B) is the correct answer.
Explanation:
Expression for the given decomposition reaction is as follows.
Let us assume that x concentration of 
is present at the initial stage. Therefore, according to the ICE table,
Initial : x 0
Change : - 0.1 
Equilibrium : (x - 0.1) 0.2
Now, expression for 
of this reaction is as follows.
Putting the given values into the above formula as follows.
x = 0.12
This means that 
= x = 0.12 atm.
Thus, we can conclude that the initial pressure in the container prior to decomposition is 0.12 atm.
Okay so because of the difference in density a simple method for telling the difference between the two is to put a sample in a container with oil, because water has a higher density than the oil it would sink to the bottom but alcohol on the other hand is lighter than oil and would float on top of the oil.
However with this question I think that what you would do is use the ice to find out what the substance is, it would float on top of the liquid if it were water because the water is denser than ice but the ice would sink if it was alcohol because the alcohol is less dense than ice.
I hope this helps you, good luck : )
