A polysaccharide 'X' on boiling with dil H₂SO₄ at 393 K under 2-3 atm pressure yields 'Y'. 'Y' on treatment with bromine water gives gluconic acid. 'X' contains $$\beta$$-glycosidic linkages only. Compound 'X' is :

Which of the following is not a broad spectrum antibiotic?

During the qualitative analysis of salt with cation y²⁺, addition of a reagent (X) to alkaline solution of the salt gives a bright red precipitate. The reagent (X) and the cation (y²⁺) present respectively are :

Atoms of element X form hcp lattice and those of element Y occupy $${2 \over 3}$$ of its tetrahedral voids. The percentage of element X in the lattice is ____________. (Nearest integer)