Two neon atoms of identical mass move along a straight line toward each other

PHYSICS · Single correct · CBSE · Physics · Work, Energy and Power · Work, Energy and Power

Problem

Two neon atoms of identical mass move along a straight line toward each other. Atom 1 moves to the right at

300\,\text{m}\!\cdot\!\text{s}^{-1}

, while atom 2 moves to the left at

100\,\text{m}\!\cdot\!\text{s}^{-1}

. They collide elastically and head-on. What is the speed of atom 1 immediately after the collision? (a)

300\,\text{m}\!\cdot\!\text{s}^{-1}

to the left (b)

300\,\text{m}\!\cdot\!\text{s}^{-1}

to the right (c)

100\,\text{m}\!\cdot\!\text{s}^{-1}

to the left (d)

100\,\text{m}\!\cdot\!\text{s}^{-1}

to the right