2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d
7s 7p
hope it helps
In 1 molecule of has 3 molecules of Oxygen. but it is given that the sample contain 6000 Oxygen atoms. therefore, the number of molecules in the sample is ~
Now, there are 8 atoms of Hydrogen in each molecule, so total number of H - atoms in 2000 molecules of the given compound would have ~
The relation between vapour pressure , enthalpy of vapourisation and temperature is
ln (88/ 39) = DeltaH / 8.314 (1 / 318 - 1 / 298)
0.814 = DeltaH / 8.314 (2.11 X 10^-4 )
DeltaH = -32.07 kJ