The Boolean equation $A \cdot \bar{A} =$ ......

In the truth table of the given circuit,the values of $X$ and $Y$ are:

$A$ logic gate is an electronic circuit which

For the following combination of logic gates,when all the three inputs $A$,$B$ and $C$ are first 'high' and then 'low',the output $Y$ will be respectively.

The output $W$ for the given logic circuit is:

Which of the following Boolean expressions is not correct?