Machanism of a hypothetical reaction ``\ce X2+ Y2`` → 2XY is given below.
( i) ``X_ 2`` → X + X (fast)
(ii) X + ``Y_2`` ``\rightleftharpoons`` XY + Y (slow)
(iii) X + Y → XY (fast)
The overall order of the reaction will be -
(1) 1.5
(2) 1
(3) 2
(4) 0