Is it possible to kill a full health (no armor) player with a single grenade? Does it make a difference if the grenade, let's say, explodes at a certain height?
According to this wiki a grenade can do a maximum of 98 damage to an unarmored enemy, and 57 to an armored one.
However throwing a grenade at an enemy's head will do 2 damage to them, therefore you can one shot someone with no armor by hitting them in the head with the grenade before it explodes near them. Here is a video demonstrating this.