Sugars are characterized by the preparation of osazone derivatives. Which sugar/s have identical osazones?

Number of stereo centers present in linear and cyclic structures of glucose are respectively:

Identify the product $\mathrm{Y}$ in following reaction $\mathrm{Maltose}\stackrel{ \mathrm{Hydrolysis} }{⟶}\mathrm{X}\underset{\left(\mathrm{excess}\right)}{\overset{\mathrm{dil}.{\mathrm{HNO}}_3}{\to }}\mathrm{Y}$

Consider the following reactions :

(i) Glucose $+\mathrm{ROH}\stackrel{\mathrm{dry}\mathrm{HCI}}{\to }\mathrm{Acetal}\underset{{\left({\mathrm{CH}}_3\mathrm{CO}\right)}_2}{\overset{\mathrm{x}\mathrm{eq}.\mathrm{of}}{\to }}$ acetyl derivative

(ii) Glucose $\stackrel{\mathrm{Ni}/{\mathrm{H}}_2}{\to }\mathrm{A}\underset{{\left({\mathrm{CH}}_3\mathrm{CO}\right)}_2\mathrm{O}}{\overset{\mathrm{y}\mathrm{eq}.\mathrm{of}}{\to }}$ acetyl derivative

(iii) Glucose $\underset{{\left({\mathrm{CH}}_3\mathrm{CO}\right)}_2\mathrm{O}}{\overset{\mathrm{z}\mathrm{eq}.\mathrm{of}}{\to }}$ acetyl derivative '$\mathrm{x}$' , '$\mathrm{y}$' and '$\mathrm{z}$' in these reactions are respectively.