Answer:
A. Semi Permeable.
Explanation:
Cell membranes are semi permeable.
Answer:
hot air rises because gases expand as they heat up.When air heats up and expands,its density also increases.The warmer,less dense air effectively floats on top of the colder, dense air below it. This creates a buoyant force that causes warmer air to rise.
cold air sinks because it is heavier as its more dense ( because of closely packed molecules) soits harder for them to move and they absorb less energy. Also, gravity pulls on it more strongly.
Hope it helps :)
I think the correct answer would be D. The reaction that involves an acid and a covalent base would be the reaction of sulfuric acid and water or H2SO4 + 2H2O → 2H3O+ + SO42– . The acid would be H2SO4 and the covalent base would be H2O since it is being held by covalent bonds and when in solution it will have equal amounts of OH- and H+ ions.
