Which of these describes the energy transformation that occurs when an athlete runs a marathon? O The chemical energy expended is less than mechanical, heat, and sound energy produced The chemical energy expended equals mechanical energy produced. O The chemical energy expended equals mechanical, heat, and sound energy produced The chemical energy expended is greater than mechanical, heat, and sound energy produced​

answer:   option a) glucagon was secreted by his pancreas before he ate the cookies because blood glucose was low. insulin was secreted after he ate the cookies because his blood glucose was high.

explanation:

it creates acid rain

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.