Which of the following has a chiral structure?

Identify the chirality of the molecules $X$ and $Y$ shown below:

Optically active $(S)-2-$methoxypropanal on reaction with $MeMgX$ gives a mixture of alcohols. The major diastereomer $P$ on treatment with $MeI / K_2CO_3$ gives an optically inactive compound. $P$ is

$A$ racemic mixture is formed by mixing which of the following?

Dichloroethene cannot exhibit ............

What is meant by configuration in an organic compound? What is meant by the reflection of a configuration?