If an endothermic reaction is non-spontaneous at freezing point of water and becomes feasible at its boiling point, then :

For the reactions
2C + O₂ $$\to$$ 2CO₂; $$\Delta H$$ = -393 J
2Zn + O₂ $$\to$$ 2ZnO; $$\Delta H$$ = -412 J

The heat required to raise the temperature of body by 1 K is called :

A heat engine absorbs heat Q₁ at temperature T₁ and heat Q₂ at temperature T₂. Work done by the engine is J (Q₁ + Q₂). This data :