Which is the best time to apply sunscreen?

Before going to bed

Just after going out in the sun

1 hour after going out in the sun

30 minutes before going out in the day

Calculate the new molarity that results when 250. mL of water is added to each of the following solutions. a) 125 mL of 0.251 M HCI B) 445 mL of 0.499 M H2SO4 C) 5.25L of 0.101 M HCO3

Calculate the molar mass of aluminum oxide (Al2O3). Express your answer to four significant figures. The molar mass of Al2O3 is grams.

How many phosphorus atoms are contained in 158 kg of phosphorus? how many phosphorus atoms are contained in 158 kg of phosphorus? 3.07 * 1027 phosphorus atoms 2.95 * 1027 phosphorus atoms 1.18 * 1024 phosphorus atoms 3.25 * 1028 phosphorus atoms 8.

Gamma rays are often used to kill microorganisms in food, in an attempt to make the food safer. Some people contend that this irradiated food is actually less safe to eat. Which, if true, would most effectively dispute their idea?

Which unit can be used to express the concentration of a solution

In an atom of argon-40 the number of protons

What statements applies to the horizontal rows or periods in the periodic table?

What can scientists measure to provide evidence that electrons can move from one energy level to another?

What type of metal is not attracted to magnets?

How are microwaves produced?