Temperature of a steel block changes from `80^(@)C` to `75^(@)C` in time `t_(1)`, from `75^(@)C` to `70^(@)C` in time `t_(2)` and from `70^(@)C` to `65^(@)C` in time `t_(3)` then . . . . . . . . .

Options

A. `t_(1)=t_(2)=t_(3)`
B. `t_(1)ltt_(2)=t_(3)`
C. `t_(1)ltt_(2)ltt_(3)`
D. `t_(1)gtt_(2)gtt_(3)`

Answer

C

Explanation

According to Newton.s law of cooling,
`(dQ)/(dt)` is proportional to the temperature differnce. It decreases as temperature decreases. So at high temperature, time is less for `5^(@)C` decrease in temperature and at lower temperature, time is more for `5^(@)C` decrease in temperature.
`:.t_(1)lt t_(2) lt t_(3)`