Cyanide is known to inhibit the flow of electrons along the electron transport chain. How would exposure to cyanide affect the pH of the outer mitochondrial compartment (the inter- membrane space)

The pH will be very High.

Explanation:

The electron chain is responsible for generating the Proton Motive Force, which pumps H+ (protons) into the inter membrane space, to lower the pH.Therefore if Cyanide inhibits the ETC, the PMF will be stopped.

Hydrogen ions will not be pumped into the inter-membrane space,to lower the pH  of the medium for increase acidity. Hence, electrochemical gradient from the diffusion of H+ back into the matrix will not  be generated,

Energy for ATP synthesis by ATPase Enzyme will not be produced. Therefore ATP synthesis will stop.

thinking it would be physical characteristics

your answer would be a, maximum exploitation of resources.