Ascientist is performing an experiment on a powder. which of the following is a sign that a chemical change has definitely occurred during his experiment?
the powder catches on fire
the powder bubbles
the power heats up
the powder brakes into small particles

Punnett squares are used to show possible combinations of alleles or to predict the probability of a trait occurring in offspring. a parakeet that is heterozygous for blue feathers (dominant) is crossed with a parakeet that is homozygous for white feathers (recessive). according to the punnett square for this cross, what percentage of offspring is predicted to have blue feathers? 25 percent 50 percent 75 percent 100 percent