On the basis of the sequence of the given reactions identify the most and least reactive elements:

X+ YA → XA + Y ...(i)


X + YB → XB + Y ...(ii)


Z + XA → ZA + X

From the sets of reactions i, ii, iii, it can be observed from i and ii that X is more reactive than Y and hence it displaces Y from its salt.


From reaction iii it can be observed that Z is more reactive than X as it displaces X from its salt.


So the most reactive element is Z and the least reactive is Y.


So correct answer is d [Z and Y].

2