Answer:
Of bond is formed by sharing of electrons - covalent
If bond is formed by donation and by accepting electrons - ionic bond
Bond formed between metals - metallic bond.
The gastric chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen, and in infancy rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis.
I believe it's B: series circuit
good luck
1 carbon and 2 oxygen atoms CO2
