According to first law of thermodynamics
- A. Mass and energy are mutually convertible
- B. Heat and work are mutually convertible
- C. Heat flows from hot substance to cold substance
- D. Carnot engine is most efficient
Answer: B. Heat and work are mutually convertible
Explanation: The First Law of Thermodynamics is a statement of conservation of energy, implying that heat and work are forms of energy and are mutually convertible.