Is silver tarnishing a chemical or physical change?

How many valence electrons does a sulfate (S04-2) ion contain? 30 32 24

What happens when you combine Mg2 and NO3

What uses does C-14 have?

John's class is doing an experiment that involves mice. The mice are kept in a large, clean cage, and John gives them water and food every day.

Which characteristic gives the most information about what kind of element an atom is? A. The atomic number B. The atomic mass C. The number of electrons D. The number of neutrons

Action - reaction forces don't cancel each other. A. True B. False

An equilibrium is dynamic. True False

In a lab, a student dissolves 6.9 g of sodium chloride (NaCl) in 125 g of water (H2O). What is the molality concentration of the solution?

Audrey is driving 50 miles in 2 hours what is her average speed?

Water has a specific heat of 4184 J / (kgK) how much energy is needed to increase the temperature os a kilogram of water 5C?