From what are chemical sedimentary rocks formed
a) chemicals weathered together
b) chemicals dissolved in water
c) chemicals cemented together
d) chemicals compacted under water

The answer is b because the chemicals dissolve under water

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.