How many chiral centres does the following compound contain?

Observed rotation of $2 \mathrm{g}$ of a compound in $10 \mathrm{mL}$ solution in a $25 \mathrm{cm}$ long polarimeter tube is $+13.4°$. The specific rotation of the compound is

Find out the concentration of the solution of a compound with an observed rotation of $+2.0°$ and a specific rotation $(16°)$ in a $1.0 \mathrm{dm}$ tube?

Identify the correct statements about the compound: 

  $$\begin{gathered} {\mathrm{CH}}_3\left(\mathrm{OH}\right)\mathrm{HC}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}\left(\mathrm{OH}\right){\mathrm{CH}}_3 \\ \left(\mathrm{Y}\right) \end{gathered}$$

(a) If stereochemistry around the double bond in $\mathrm{Y}$ is cis, the number of enantiomers possible for $\mathrm{Y}$ is $2$.

(b) There are $4$ meso stereoisomers possible for $\mathrm{Y}$.

(c) Total number of stereoisomers possible for $\mathrm{Y}$ is $4$.

(d) All stereoisomers of $\mathrm{Y}$ are optically active.

Identify the correct statements about the following:

w            

x 

y          

z