On heating a mixture of common salt and $K_2Cr_2O_7$ in equal amount along with concentrated $H_2SO_4$ in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas respectively are:

The correct statements are :

A. Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.

B. During denaturation, secondary and tertiary structures of a protein are destroyed but primary structure remains intact.

C. Nucleotides are joined together by glycosidic linkage between $\mathrm{C}_1$ and $\mathrm{C}_4$ carbons of the pentose sugar.

D. Quaternary structure of proteins represents overall folding of the polypeptide chain.

Choose the correct answer from the options given below :

Statement I : Compound (X), shown below, dissolves in NaHCO₃ solution and has two chiral carbon atoms

Statement II : Compound (Y), shown below, has two carbons with sp³ hybridization, one carbon with sp² and one carbon with sp hybridization

In the light of the above statements, choose the correct answer from the options given below :

A. Mn forms the oxide $\mathrm{Mn_2O_7}$, in which Mn is in its highest oxidation state.

B. Oxygen stabilizes the Mn in higher oxidation states by forming multiple bonds with Mn.

C. $\mathrm{Mn_2O_7}$ is an ionic oxide.

D. The structure of $\mathrm{Mn_2O_7}$ consists of one bridged oxygen.

Choose the correct answer from the options given below :