Answer:
Y Q W Z X
Explanations:
The most reactive element is the element that will displace an element from it compound . The most reactive element will replace the less reactive element in it compound.
Q+ + Y Reaction occurs
Since the reaction occurs the element Y which is more reactive displaced element Q from it compound.
Q+W+ Reaction occurs
The reaction occurs, that means element Q replaces element w from it compound. Element Q is therefore more reactive than element W.
W+Z+ Reaction occurs
The reaction also occurs . This is an indication that element W replaces element Z in it compound. This means element W is very reactive than element Z.
X+Z+ No reaction
There is no reaction here. This is an indication that element X is less reactive than element Z. This is why element X can't displace element Y in it compound.