1) Explain what a covalent bond is.

its a chemical link between two atoms or ions in where the electron pairs are shared between them :)

Explanation:

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: