Answer:
v = 4.15 10⁴ m / s 
Step-by-step explanation:
Suppose that all the energy in the battery is converted into kinetic energy of the proton 
 U = K 
 q V = ½ m v² 
 v = √ 2q V/m
 
 v = √ (2 1.6 10⁻¹⁹ /1.67 10⁻²⁷ 9) 
 v = √( 17.2455 10⁸) 
 v = 4.15 10⁴ m / s 
 
Relativistic corrections are not needed as this speed is much less than the speed of light