Yes. By lighting TNT with fire, (lava, flint and steel), the TNT will start to blow up.
I assume you mean TNT. All you have to do is hit it.
It is physically impossible to make your pen explode unless you use TNT.
If you mean classic (Which I think you do) It wasn't made to explode (as is: It can't)
Well there can be tnt.
They should have updated it by now to have the Flint and steel
Not without a mod. 303 Arrows mod is good for what you are looking for but I think it is outdated
Dynamite ! , & TNT .
The previous way to explode TNT was by punching it. However, you can also make the TNT explode by placing it near lava (a timely manner to explode it), clicking on it with flint and steel, or any contact with fire. If you were not in classic, it could also be ignited by Redstone or fire charge or even a fire arrow (assuming you have the latest version of Minecraft). In the related links below, I have listed the wiki article for TNT.
If TNT explodes while in water it will not destroy blocks but will damage any mobs (players, animal or monsters) in the blast radius.
People are stupid enough to stuff TNT into it ...
There is such a thing as spontaneous combustion. Not normally though. Unless you deliberately explode it. There is such a thing as spontaneous combustion. Not normally though. Unless you deliberately explode it.
There's currently no way.