Why is respiration an exothermic reaction? a. a large amount of energy is released into its surroundings b. the heat content, q, of the reaction is positive c. a large amount of energy is required to activate the reaction d. there is no exchange of energy between the system and the surrounding

A. a large amount of energy released into its surrounding

During the respiration, glucose molecules are converted to other molecules in a series of steps. They finally end up as as carbon-dioxide and water.

The overall reaction is

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 2805 kJ

The reaction is exothermic reaction because C=O and O-H bonds in the products are so much more stable than the bonds in the reactants.

Bond energy is the average needed to break a bond.

Some bond energies are:
C-C = 347 kJ/mol
C-H = 413kJ/mol;
C-O = 358 kJ/mol;
O-H = 467 kJ/mol;
O=O = 495 kJ/mol;
C=O = 799 kJ/mol

The density of the block of iron is lees than the density of mercury but the density of the block of iron is greater than the density of water