6. When water in a lake freezes, the ice that forms floats on top of any water that is still liquid. Why does the ice float?
A
Ice is less dense than liquid water, so it floats.
B.
Air bubbles trapped in the ice cause the ice to float.
C. Ice crystals are polar, and they float on top of non-polar water.
D.
The ice forms at the top of the water, so it stays there and floats.

Which best explains why viruses do not have special structures or enzymes that allow them to make their own food? viruses can use energy in living cells that they infect. viruses can replicate inside a host that they infect. viruses can cause contagious illnesses in host cells. viruses integrate their rna or dna into infected cells.

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?

Which was most likely an effect on society that resulted from improvements in blood handling during world war i and world war ii?