An immersion heater, in an insulated vessel of negligible heat capacity brings 10 g of water to the boiling point from `16^@C` in 7 min. Then
Q. The water is replaced by 200 g of alcohol, which is heated from `16^@C` to the boiling point of `78^@C` in 6 min 12 s whereas 30 g are vapourized in 5 min 6 s. The specific heat of alcohol is

Options

A. `0.6 J//kg^@C`
B. `0.6 cal//g^@C`
C. `0.6 cal//kg^@C`
D. `6 J//kg^@C`

Answer

B

Explanation

With 200 g of alcohol in the vessel, the temperature Quantity of heat absorbed by alcohol
`Q_a=C_am_a(theta_f-theta_i)`
`=C_axx(200g)(78-16)^@C`
Heat given by heater
`Q_a=Pt_2=(20(cal)/(s))xx372s`
Specific heat of alcohol
`C_a=(20xx372)/(200xx62)=0.6(cal)/(g^@C`
`=(0.6xx4.186J)/(10^-3kg^@C)=2.5xx10^3(J)/(kg^@C)`
`=2.5(K)/(g^@C)`