Most stable carbocation among the following is

Which of the following compounds is chiral but does not contain a chiral carbon?

Which of the following statements is not correct about the compound $(I)$ shown below?
$(I)$ = $3-$bromocyclopropene

The number of stereoisomers possible for a compound of the molecular formula $CH_3-CH=CH-CH(OH)-CH_3$ is:

Identify the correct sequence for True and False.
$(I)$ Only compounds with chiral centers can be optically active.
$(II)$ Absence of elements of symmetry is the reason for a molecule's optical activity.
$(III)$ All organic compounds contain carbon $\&$ hydrogen.
$(IV)$ Different canonical forms of a molecule represent the actual structures of a molecule which has resonance in it.

At normal temperature,$X$ and $Y$ are: