Read the following statements : A . When small temperature...

$A$. by Newton's law of cooling $- \dfrac{d\theta}{dt} ∝ \Delta\theta$

$B$. According to Stephan's law $\dfrac{d H}{d t} = \sigmaeA{T}^{4} ⇒ \dfrac{{H}_{P}}{{H}_{Q}} = {\left(\dfrac{{T}_{P}}{{T}_{Q}}\right)}^{4} = {\left(\dfrac{283}{293}\right)}^{4}$

$⇒ {H}_{P}: {H}_{Q} = 1{\left(1 . 03\right)}^{4} = 1: {\left(1 . 03\right)}^{4} = 1: 1 . 15$

$⇒ B$ is correct

$C$. The efficiency of the Carnot cycle is given by$η = 1 - \dfrac{{T}_{1}}{{T}_{2}} = 1 - \dfrac{100}{400} = \dfrac{3}{4} = 75$

$D$. is wrong as according to the Newton's law of cooling $\dfrac{d\theta}{dt} ∝ \DeltaT$