17. how many moles are there in a sample containing 1000 molecules of h2o? 18. if you wanted a sample of h2o containing 6 x 23molecules, how could you measapproximate number without counting?

17) mol of  = 
                            = 
                            = 1.658  *   

18) mol = 
      
      Let mass of oxygen = x
      
     
             =  17.9 g

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

Is a logical series of steps