A researcher studying organic compounds has found that five different molecules. T, W, X, Y and Z form chains according to the following rules :
A chain consists of three or more molecules, though the molecules in the chain are not necessarily different.
T is never found on either end of a chain.
If W appears in a chain, it appears more than once.
X is never found next to y in a chain.
W is never found on the end of a chain
unless Z is found somewhere in the chain.
If Y appears in a chain, Z appears also,
Which of the following sequences can be converted into a chain by adding Z and rearranging the molecules ?
I. X Y X T
II. W T T Z
III. X X Y W
Solution
XYXTZ forms a valid chain.
WTTZ and XXYW can not form a valid chain with Z because W should appear twice.
Thus, only I will be a valid chain with an additional Z.
