Correct Answer - A
According to law of conservation of energy Sum of potential energy and kinetic energy remain constant Now initially proton starts from rest. Hence, kinetic energy of proton at initial point is zero but it has potential energy
`PE = qv`
where `q=1.6xx10^(-19)` C and V =1000V
Assuming the proton no longer experiences the potential energy and it is all converted to kinetic energy
`PE^(**)=0, KE^(**)=1/2mv^(2)`
Since, `KE +PE` = total energy `=PE^(**)+KE^(**)`
`qv+0+0+1/2mv^(2) or KE=qv=1.6xx10^(-16)` J=1 keV
