Which of the following explains why elements in column 17 (the halogens) are very reactive?
their atoms contain three energy levels.
their atoms need only one electron to complete their outer energy level.
their atoms have large masses.
their atoms contain the same number of protons as electrons.

Galactosemia is an autosomal recessive disorder caused by the inability to metabolize galactose, a component of the lactose found in mammalian milk. galactosemia can be partially managed by eliminating dietary intake of lactose and galactose. amanda is healthy, as are her parents, but her brother alonzo has galactosemia. brice has a similar family history. he and his parents are healthy, but his sister brianna has galactosemia. amanda and brice are planning a family and seek genetic counseling. based on the information provided, complete the following activities and answer the questions.a) draw a pedigree that includes amanda, brice, their siblings, and parents. identify the genotype of each person, using g and g to represent the dominant and recessive alleles, respectively.b) what is the probability that amanda is a carrier of the allele for galactosemia? what is the probability that brice is a carrier? explain your reasoning for each answer.c) what is the probability that the first child of amanda and brice will have galactosemia? show your work.d) if the first child has galactosemia, what is the probability that two of the next three children will not have galactosemia? show your work and explain the reasoning for your answer.