When isomers have the same structural formula but differ in the relative arrangement of atoms or groups,they are called ........

Which of the structures given below are chiral?

$(i)$ Number of geometrical isomers for the given structure $X$ (assuming $X$ contains $3$ stereogenic double bonds):
$(ii)$ Number of cyclic structural isomers with molecular formula $C_5H_{10} = Y$
$(iii)$ Number of ethers with molecular formula $C_4H_{10}O = Z$
Find the value of $X + Y + Z$.

Which one of the following is most stable?

What are isomers? State the types of isomerism.

The possible number of stereoisomers for $5-$phenylpent$-4-$en$-2-$ol is $.............$