Based on the periodic table, which of the following groups of elements should have very different chemical properties?
A.
beryllium (Be), magnesium (Mg), calcium (Ca)
B.
helium (He), neon (Ne), argon (Ar)
C.
lithium (Li), sodium (Na), potassium (K)
D.
potassium (K), aluminum (Al), neon (Ne)

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

let that person have a turn to speak : )