The correct answer is B = 4.2 joule
The calorie is a unit of energy defined as the amount of heat needed to raise a quantity of water by one degree of temperature. For historical reasons, two main definitions of calorie are in wide use.A calorie is a unit of energy. When you hear something contains 100 calories, it's a way of describing how much energy your body could get from eating or drinking it.
The calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius. Since 1925 this calorie has been defined in terms of the joule, the definition since 1948 being that one calorie is equal to approximately 4.2 joules.
- For a mass m = gm = kg.
- with specific heat c = cal/gm°C = joule/gm°C,
- initial temperature Ti = °C = K = °F.
- and final temperature Tf = °C = K = °F,
- Q = calories = kcal = x 10^ calories.
- Q = joules = x 10^ joules.