List two examples of a physical change :

Explain why desert soils tend to be rich in minerals but poor in topsoil

What did rutherford discover that thomson did not understand? A) that an atom's electrons took up as much space as its nucleus.

The atomic number of manganese is 25; its mass number is 55. How many neutrons does an atom of manganese have in its nucleus? a) 25 b) 80 c) 30 d) 55

How many electrons do you need to match the weight of a proton

How many valence electrons does a nitrogen atom have?

47 When the pH of an aqueous solution is changed from 1 to 2, the concentration of hydronium ions in the solution is (1) decreased by a factor of 2 (2) decreased by a factor of 10 (3) increased by a factor of 2 (4) increased by a factor or 10

Which is easier to observe the physical or chemical properties of an object? Support your answer with evidence

How many moles are in 20 grams of sodium

Elements in the noble gas family are considered stable because

A race car driver starts a race with his tires at 13.2 psi at a temperature of 25 C. What will the pressure in the tires be (in psi) when they heat up to 63 C?