PLEASE HELP M What type of sunscreen can best reduce risk of melanoma? SPF 4 used daily SPF 4 used once a month SPF 15 or higher used daily SPF 15 or higher used once a month -this is science-

Asolution is made by dissolving 25.5 grams of glucose (c6h12o6) in 398 grams of water. what is the freezing point depression of the solvent if the freezing point constant is -1.86 °c/m? show all of the work needed to solve this problem.

In a water molecule, hydrogen and oxygen are held together by a(an) bond. a) double covalent b) ionic c) nonpolar covalent d) hydrogen e) polar covalent

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6