Rohit and Mayuri conducted two experiments to study the types of chemical reactions as shown in the given figures.
They recorded their observations as :
I. In experiment 1, yellow residue is left behind while in experiment 2 reddish brown solid is left behind.
II. In both experiments, two different gases were given out.
III. The colourless gas evolved in experiment 1 extinguishes the glowing splint while the gas evolved in experiment 2 turns green solution of acidified `KMnO_4` orange.
IV. X is reddish brown gas while gases Y and Z both have burning sulphur smell.
The incorrect observation(s) is/are
