Which of the following are isostructural pairs ?

A. $$SO_4^{2 - }$$ and $$CrO_4^{2 - }$$

B. SiCl₄, and TiCl₄

C. NH₃ and NO₃^-

D. BCl₃ and BrCl₃

Consider the elements Mg, Al, S, P and Si, the correct increasing order of their first ionization enthalpy is :

Out of the following, which type of interaction is reponsible for the stabilisation of $$\alpha $$-helix structure of proteins ?

Which of the following compound gives pink colour on reaction with phthalic anhydride in conc. H₂SO₄ followed by treatment with NaOH ?