Question 1
elements in the same period have the same

valence electron
electrons
atomic number
valence shell number

question 2
which element has the greatest reactivity? (refer to a periodic table)

phosphorous (p)
chlorine (cl)
sodium (na)
lithium (li)

the answer to your question is slate

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: