Question

4. The amount of heat energy required to increase the temperature of X g of water by 10⁰C is found to be 15 cal. Calculate X.

• A. 0.5 g
• B. 15 g
• C. 1.5 g
• D. 7.5 g

Answer 1

The correct option is C

1.5 g

Explanation:

Step 1: Specific heat

Specific heat: specific heat is the heat required to raise the temperature of unit mass by 1⁰C.

Specific heat is denoted by C.

The specific heat of pure water is 1 Cal/g/⁰C.

And the formula of specific heat i.e., $\mathrm{Q}=\mathrm{mc}∆\mathrm{t}$

Q=heat energy

m= mass

c=specific heat

t=temperature

Step 2: Calculation of X

Since, the specific heat of pure water is 1 Cal/g/⁰C.

Therefore, C = 1 Cal/g/⁰C

Q= 15 Cal ,

m= x

t = 10^oC

Since,

$$\begin{gathered} \mathrm{Q}=\mathrm{mc}∆\mathrm{t} \\ \mathrm{Therefore}, \\ 15=\mathrm{m}\times 1\times 10 \\ \mathrm{m}=\mathrm{x}=\frac{15}{10} \\ \mathrm{m}=\mathrm{x}=1.5\mathrm{g} \\ \mathrm{or} \\ \mathrm{x}=1.5\mathrm{g} \end{gathered}$$

Hence, (C) is the correct option.