Which of the following reagent is used for the following reaction ?

$$ \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_3 \stackrel{?}{\longrightarrow} \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO} $$

The gas released during anaerobic degradation of vegetation may lead to :

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 :