What shape do ice crystals have? How does hydrogen bonding cause that shape?

Iknow #2 is d. i just need to know why

Maria wants to determine which type of disinfectant kills the most bacteria. which of the following is the best way for maria to determine this? a. ask ten different companies that make disinfectants which type is best. b. put the same amount and species of bacteria on ten identical plates, and add ten different kinds of disinfectant to each plate. c. interview ten different people to determine which type of disinfectant they prefer. d. put the same amount and species of bacteria on ten identical plates, and add a different disinfectant to each plate.

This element exists in adundance in the sun.explain how you would go about capturing sunlight.would this captured sunlight contain any of the element?