What are elements in the same row or period called

Why do people put on sunscreen to protect from ultraviolet light but don't try to protect themselves from infrared light? Refer to EM spectrum to answer

If 36.0 g of so2 is produced, what is the percent yield for the reaction?

Identify the characteristics that describe how human proteins are assembled. Check all that apply.

1. List the three states of water shown here.

The price of gold on April 15,2000 was $282/t. oz. How much did 100.0cm^3 of gold cost that day if 1.00 t. oz=28.4 grams?

A sample of hydrogen gas at 2.0 atmospheres and 273 k occupies a volume of 5.0 liters. the gas sample is completely transferred to a 10.0-liter sealed, rigid container.

To make sure that the white powder was all sodium chloride and not mixed with sodium hydrogen carbonate, would you need to add a little less or a little more hydrochloric acid to the reaction?

A 10.0 gram sample of h2o at 23.0c absorbs 209 joules of heat. what is the final temperature

What does the sum of the protons and neutrons in an atom equal

Which gas sample at STP has the same total number of molecules as 2.0 liters of CO2 (g) at STP