Lithium contains two isotopes: Lithium-6 and Lithium-7. Lithium-6
makes up 7.5% of the world's total
lithium, while Lithium-7 makes up
92.5%. Calculate its average atomic
mass.

What are the similarities of physical and chemical change ?

If 15 drops of ethanol from a medical dropper weight 0.60g, how many drops does it takes from a dropper to dispense 1.0ml of ethanol? the density of ethanol is 0.80g/ml

Suppose you mix one mole of sulfuric acid (h2so4) with 1 mole of sodium hydroxide(naoh). why does the ph of the solution remain below 7? ( explain so i can get better understanding! )