${\mathrm{CH}}_2\mathrm{OH}(\mathrm{CHOH}{)}_4\mathrm{CHO}+\mathrm{HCN}\to \mathrm{X}$

Identify the compound $\mathrm{X}$ in the above reaction?

Which of the following processes/reactions will give a diastereomeric pair in the resulting solution?

(a) Mutarotation of glucose

(b) Ekenstein rearrangement of D-mannose

(c) Acidic hydrolysis of cane sugar

(d) Open form of D-glucose with $\mathrm{HCN}$

Given: specific rotation of $(+)$ sucrose, $(+)$ maltose, $\mathrm{L}(-)$ glucose, $\mathrm{L}(+)$ fructose in aqueous, solution are $+66°,+140°,-52°$and$+92°$respectively. For 'invert sugar', the correct statements are?

(a) 'Invert sugar' is prepared by acid-catalyzed hydrolysis of maltose

(b) 'Invert sugar' is an equimolar mixture of $\mathrm{D}(+)$ glucose and $\mathrm{D}(-)$ fructose

(c) Specific rotation of  'invert sugar' is $(-20°)$

(d) On reaction with ${\mathrm{Br}}_2$ water ' invert sugar' forms saccharic acid as one of the products.

Amino acids are classified as acidic, basic, or neutral depending upon the relative number of amino and carboxyl acid groups in their molecule. Which among the following are acidic?