so, $\frac{{KA({\theta _1} - {\theta _2})t}}{l} = m \times L$
$ \Rightarrow m = \frac{{{{10}^{ - 3}} \times 92 \times (100 - 0) \times 60}}{{1 \times 8 \times {{10}^4}}} = 6.9 \times {10^{ - 3}}kg$


$Reason :$ Air surrounding the fire conducts more heat upwards.
$A.$ When small temperature difference between a liquid and its surrounding is doubled the rate of loss of heat of the liquid becomes twice.
$B.$ Two bodies $P$ and $Q$ having equal surface areas are maintained at temperature $10^{\circ}\,C$ and $20^{\circ}\,C$. The thermal radiation emitted in a given time by $P$ and $Q$ are in the ratio $1: 1.15$
$C.$ A carnot Engine working between $100\,K$ and $400\,K$ has an efficiency of $75 \%$
$D.$ When small temperature difference between a liquid and its surrounding is quadrupled, the rate of loss of heat of the liquid becomes twice.
Choose the correct answer from the options given below :