A) 50s
B) 100s
C) 150s
D) 200s
Correct Answer: C
Solution :
[c] Let time taken in boiling the water by the heater is t second. Then, |
\[Q=ms\Delta T\Rightarrow \frac{Pt}{J}ms\Delta T\] \[(\because Q=W=Pt)\] |
\[\therefore \] \[\frac{836}{4.2}t=1\times 1000(40-10)\] \[(1C=4.2J)\] |
\[\frac{836}{4.2}t=1000\times 30\] |
\[t=\frac{1000\times 30\times 4.2}{836}=150\,s\] |
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