Mass of the following `"element" // "compound"` is given in grams. Calculate it.s moles and number of `"molecules"//"atoms"` :
2 g water `(H_(2)O)`

Explanation

Number of moles of 2g `H_(2)O= ("mass of water")/("molecular mass of water")`
`=(2)/(18)`
`=(1)/(9)` mole
Number of molecules in 2 g water `(H_(2)O) = "Number of moles of "H_(2)O xx "Avogadro number"`
`=(1)/(9)" mole" xx 6.023 xx 10^(23) "molecules"// "mole"`
`~~ 0.6692 xx 10^(23)` molecules
`~~ 6.692 xx 10^(22)` molecules