The brain can use for energy. select one: a. only glucose b. only fats c. only ketones d. only lactate e. both glucose and ketones

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Amniocentesis is a process in which amniotic fluid is taken from the mother's womb to identify any genetic abnormalities in the fetus. how would the discovery of the human genome contribute to this process?

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?