L-isomer of tetrose $$\mathrm{X}\left(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{4}\right)$$ gives positive Schiff's test and has two chiral carbons. On acetylation, '$$\mathrm{X}$$' yields triacetate. '$$\mathrm{X}$$' also undergoes following reactions

'$$\mathrm{X}$$' is

Which of the following complex has a possibility to exist as meridional isomer?

Arrange the following compounds in increasing order of rate of aromatic electrophilic substitution reaction

A solution of sugar is obtained by mixing $$200 \mathrm{~g}$$ of its $$25 \%$$ solution and $$500 \mathrm{~g}$$ of its $$40 \%$$ solution (both by mass). The mass percentage of the resulting sugar solution is ___________ (Nearest integer)