How many phases of matter are there

Seawater contains approximately 3.5%nacl by mass and has a density of 1.02 g/ml. what volume of seawater contains 7.5 g of sodium?

One mole of zinc has a mass of 65.4 grams. approximately how many atoms of zinc are present in one mole of zinc? 32 × 1023 atoms 6 × 1023 atoms 66 atoms 65 atoms

What is conserved in the reaction shown below? h2(g) + cl2 (g) --> 2hcl(g)a. mass onlyb. mass and moles onlyc. mass, moles, and molecules onlyd. mass, moles, molecules, and volume