If instantaneous rate of reaction is given as $$ -\frac{1}{\mathrm{a}} \frac{\mathrm{~d}[\mathrm{~A}]}{\mathrm{dt}}=-\frac{1}{\mathrm{~b}} \frac{\mathrm{~d}[\mathrm{~B}]}{\mathrm{dt}}=\frac{1 \mathrm{~d}[\mathrm{C}]}{\mathrm{c}]}=\frac{1 \mathrm{~d}[\mathrm{D}]}{\mathrm{d}]}$$

the reaction is represented as

Which among the following is a correct decreasing order of thermodynamic stability of the complexes?

Identify the process from following such that volume of system remains constant.

Identify the instrument used to find crystal structure from following :