Answer:
Less than 0.033 M:
![[Z]_{eq}=2.4x10^{-3}M](https://tex.z-dn.net/?f=%5BZ%5D_%7Beq%7D%3D2.4x10%5E%7B-3%7DM)
Explanation:
Hello,
In this case, the described equilibrium is:

Thus, the law of mass action is:
![K=\frac{[Z]^2}{[A]^2[B]}=0.43](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5BZ%5D%5E2%7D%7B%5BA%5D%5E2%5BB%5D%7D%3D0.43)
Nevertheless, given the initial concentration of Z that is 0.033 M, we should invert the equilibrium since the reaction will move leftwards:
![\frac{1}{K}=\frac{[A]^2[B]}{[Z]^2}=\frac{1}{0.43}=2.33](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BK%7D%3D%5Cfrac%7B%5BA%5D%5E2%5BB%5D%7D%7B%5BZ%5D%5E2%7D%3D%5Cfrac%7B1%7D%7B0.43%7D%3D2.33)
Know, by introducing the change
due to the reaction extent, we can write:

Which has the following solution:

But the correct solution is
since the other solutions make the equilibrium concentration of Z negative which is not possible. In such a way, its concentration at equilibrium is:
![[Z]_{eq}=0.033M-2(0.0153M)](https://tex.z-dn.net/?f=%5BZ%5D_%7Beq%7D%3D0.033M-2%280.0153M%29)
![[Z]_{eq}=2.4x10^{-3}M](https://tex.z-dn.net/?f=%5BZ%5D_%7Beq%7D%3D2.4x10%5E%7B-3%7DM)
Which is clearly less than 0.033 M since the addition of a product shift the reaction leftwards in order to reestablish equilibrium (Le Chatelier's principle).
Regards.
A hope it helps ur welcome
Option (C) is the correct answer.
In the chemical reaction, reactants are the starting elements or compounds which will chemically react and will form the products. Reactants are only present on the left hand side of the reaction and products are present on the right hand side of the reaction.
Reactants present in the reaction is completely used up in the reaction to form products implies no traces of reactants will be present in the product side.
For example:

Here, hydrogen and oxygen are the reactants whereas water is the product (new substance). Hydrogen reacts with oxygen and form water i.e. hydrogen and oxygen is completely used up in the reaction to form new substance i.e. water.
Hence, substances that are used up in a reaction is known as reactants of the reaction.
The most dense one out of all of the answers would be the glass marble with a higher density than that of the golf ball and the rubber ball