Explain why elements and compounds are pure substances

A 0.250 M solution of HCN has a pH = 4.87. a) Determine the [H3O+] in the solution. b) Calculate the percent ionization of HCN in this solution.

How much mass would a nucleus that is composed of 15 protons and 18 neutrons have?

What does the atomic mass describe? a. The mass of the protons in the atom b. The mass of the nucleus of the atom c. The mass of the neutrons in the atom d. The mass of the electrons in the atom

Mass in grams of 4.26 mol Si

Is breaking a pretzel physical change or chemical change

Reactions cannot occur without a certain minimum amount of energy. what is this minimum amount of energy called?

What are the products of the alpha decay of Iodine-131?

Which lewis electron-dot diagram represents a nitrogen atom in the ground state

What would a 1:1 liquid binary mixture of Cyclohexane and Toluene look like? How would the molecules associate with one another?

A sample of argon gas is at a pressure of 1.725x10^4 kPa and a temperature of 24°C in a rigid 20 L tank. How many moles of argon does this tank contain? (show your work)