9701 MCQ Solution 15

Question 15: [Physical > Electrochemistry]:

The propellant used in the solid rocket booster of a space shuttle is a mixture of aluminium and compound X. Compound X contains chlorine in an oxidation state of +7.

Which of the following could be compound X?

A NH₄Cl

B NH₄ClO₃

C NH₄ClO₄

D N₂H₅Cl

Reference: Past Exam Paper – November 2002 Paper 1 Q15

Solution 15:

Answer: C.

In option C, NH₄ is the ammonium ion with a +1 charge. O has a constant charge of -2, thus 4 of them will have an overall charge of -8. For the molecule to be electrically neutral the Cl atom would be required to have a +7 charge, hence the chlorine atom would exist in the +7 oxidation state.