See the meaning of Real a/c...it applies to assets(u shld knw the meaning of asset) Similarly Personal a/c applies to person both natural and artificial a/cs. Nominal a/cs to Exp. loss, income and gains.
Accounting is not merely blindly following rules of accounting, one should record the transactions keeping in view the happening i.e what is actually happening in tat transaction and the future consequences of it.
In ur illustration,
There is cash purchase of stationery, this is what happening in relation to the transaction. If u see the future events in regards this,there is absolutely no effect on future events directly, in other words, there is cash purchases n u will not be interested to knw who the party is as its not on credit. If it would hv been on credit u would hv brought XYZ store into ur books by applying Personal A/c rule( Cr . the giver) so that it would be knwn tat u hv to pay xyz store.
coming to ur 2nd & 3rd view point, Pens are stationery which r not assets(Pens dnt give benifit fr more than ayear) so it has to be rcrded as per nominal A/c rule by debiting Stationery exp.A/c.... Cash is gng out apply rule of real A/c by crediting cash A/c
Hence entry wiil be.. Stationery Exp. A/c Dr.
To cash A/c
Hope i hv shed some light. In my opinion u shld practise basics of A/cs with applicablity of concepts and principles. Accounting Is not recording of some numbers rather it is recording of what is happening in monetory terms with reference to past, present and future effects.....