Can you throw back a bomb thrown by an alchemist with Snatch Arrows?

Question

An alchemist has the ability to throw bombs.

His opponent is a monk with the Snatch Arrows feat.

Snatch Arrows (Combat)

Instead of knocking an arrow or ranged attack aside, you can catch it in mid-flight.

Prerequisites: Dex 15, Deflect Arrows, Improved Unarmed Strike.

Benefit: When using the Deflect Arrows feat you may choose to catch the weapon instead of just deflecting it. Thrown weapons can immediately be thrown back as an attack against the original attacker (even though it isn’t your turn) or kept for later use.

You must have at least one hand free (holding nothing) to use this feat.

Deflect Arrows (Combat)

You can knock arrows and other projectiles off course, preventing them from hitting you.

Prerequisites: Dex 13, Improved Unarmed Strike.

Benefit: You must have at least one hand free (holding nothing) to use this feat. Once per round when you would normally be hit with an attack from a ranged weapon, you may deflect it so that you take no damage from it. You must be aware of the attack and not flat-footed. Attempting to deflect a ranged attack doesn’t count as an action. Unusually massive ranged weapons (such as boulders or ballista bolts) and ranged attacks generated by natural attacks or spell effects can’t be deflected.

If he as a free hand, can he throw back a bomb supposed to explode on impact ?

Answer 1

You can catch them, but you cannot use them.

Alchemist's bombs cannot be used or carried by anyone else other than the alchemist who created them:

An alchemist’s bomb, like an extract, becomes inert if used or carried by anyone else.

This means you can deflect and even catch a bomb, but you cannot throw it back and expect it to explode (it won't). If you throw it back, expect it to be an improvised throw weapon and cause equivalent damage to throwing a vial or cup of glass at someone (probably 1d2 or 1d3 damage).

This also means that, even if the alchemist creates a bomb and hands it over to a friend so they can throw it, the bomb becomes inert as soon as it is held by another character.

James Jacobs (Paizo's Creative Diretor) also confirms that bombs, being ranged attacks, can be deflected by monks (and whoever has the feat).

The bomb still explodes if deflected, but since it is not directly hitting your character, she takes no damage from it. Normally, missing a bomb would cause at least the splash damage, but the character is protected from the text of Deflect Arrows:

Once per round when you would normally be hit with an attack from a ranged weapon, you may deflect it so that you take no damage from it.

Everyone else within the splash radius should still take damage from the explosion if the bomb is deflected, but not if the bomb is snatched. If a bomb is snatched, it did not hit any target, not even the ground. If there is no direct hit, the bomb doesn't cause splash damage.

A hit deals direct hit damage to the target, and splash damage to all creatures within 5 feet of the target.

Answer 2

Yes

The "ranged weapon" denomination in Deflect Arrows covers thrown weapons (that's not clear but considering that Snatch Arrow have a special section for thrown weapons it seems intended). It's not a "massive ranged weapon" (unless thrown at a very small monk) neither it's "generated by natural attack or spell effects": Deflect Arrows should work.

Snatch Arrow doesn't raise any other constraints on the kind of weapons, so bombs can be snatched too.

Note1: in the rules about Alchemist's bombs:

Bombs are unstable, and if not used in the round they are created, they degrade and become inert

So you can't snatch the bomb and keep it for later, you have to use it before they degrade (it's not clear if "the round they are created" ends at the beginning of the alchemist's next round but it seems to be a coherent interpretation).

Note2: one could argue that this ruling is not realistic, but Snatch Arrow is never realistic to start with, even with regular projectiles. Physical considerations like momentum don't work well with Pathfinder rules.

Answer 3

That depends on how the bomb's explosion is triggered. If it is triggered by an impact, the change of speed and momentum from catching it would let it explode in the monk's hand. If it is triggered after a predefined time independent of what happens in the meantime, this is viable as the possibility to immediately throw back a thrown weapon is explicitly described. You therefore should ask for additional information from the GM or player on the type of bomb and its explosion mechanism.