how many moles are present in 9g of water

given weight=9g                                                                                                                                                                            molecular weight = 2+16= 18g                                                                                                                                                  by using formmula,   no. of moles= given weight divided by molecular weight                                                          9/18= 0.5 mole

Water(H₂O) has a molecuar mass of 18, this means it weights 18 g per mole. A mole is 6.0221415*10²³molecules (Avogadro's number). If you have 1 g of water, you therefore have 1/18 of a mole, or 3.34*10²² molecules.

and in 9 gm of water you have 9/18 of mole or 3.011*10^{23  molecules}