If 'white' is called 'bird', 'bird' is called 'mercury', 'mercury' is called 'curd', 'curd' is called 'detergent' and 'detergent' is called 'white', then which of the following is used in 'thermometers'?

curd

Given; If 'white' is called 'bird', 'bird' is called 'mercury', 'mercury' is called 'curd', 'curd' is called 'detergent' and 'detergent' is called 'white'

So,

WORDS  white     bird      mercury   curd       detergent

CODES   bird    mercury     curd    detergent    white

Thus,

Mercury i used in thermometers and the code is curd.