Which one of the following circuits is NOT equivalent to a $$2$$-input $$XNOR$$ (exclusive NOR) gate

Consider the following circuit involving three Dtypes flip-flops used in a certain type of Counter configuration.

If at some instance prior to the occurrence of the clock edge, $$P, Q$$ and $$R$$ have a value $$0,1$$ and $$0$$ respectively, what shall be the value of $$PQR$$ after the clock edge?

Consider the following circuit involving three Dtypes flip-flops used in a certain type of Counter configuration.

If all the flip-flops were reset to $$0$$ at power on, what is the total number of distinct outputs (states) represented by $$PQR$$ generated by the counter?

If the difference between the expectation of the square of a random variable $$\left( {E\left[ {{X^2}} \right]} \right)$$ and the square of the expectation of the random variable $${\left( {E\left[ X \right]} \right)^2}$$ is denoted by R then