A helium atom has 2 protons and 2 neutrons. what is the mass number of this atom?

What is the symbol of the element that is classified as an alkali metal and is in period 4?

Does absorbance increase or decrease as the solution concentration of the absorbing substance increases?

A solid with a density of 3.57g/mL and mass of 19.5g is added to a graduated cylinder that contain 23.2mL of water. What is the volume of the liquid once the solid is dropped in the cylinder?

Luminum reacts with sulfuric acid to produce aluminum sulfate and hydrogen gas. in this reaction, what is the formula for sulfuric acid

How many moles of br2 (l) (mm = 159.80 g/mol) are in 13.9 ml of liquid bromine? the density of br2 (l) is 3.12 g/ml?

An 8.5 g ice cube is placed into 255g of water. Calculate the temperature change of water when the ice melts

If you knew the number of valence electrons in a nonmetal atom, how would you determine the valence of the element?

Which of the following solutions is a good buffer system? Which of the following solutions is a good buffer system? a solution that is 0.10 M HF and 0.10 M LiC2H3O2 a solution that is 0.10 M HC2H3O2 and 0.10 M LiC2H3O2 a solution that is 0.

Which formula shows a substance that is not molecular?

Brainstorm how you could run a pcr reaction if you did not have access to a thermal cycler.