The unit of work is MCQ with Answer and Explanation

Explanation:
Protium 0 neutrons, Deuterium 1, Tritium 2.

Explanation:
Position-time graph as parabola: x = x₀ + ut + ½at². This quadratic form indicates constant acceleration 'a'. If acceleration were changing, the graph would be cubic or higher order. Constant velocity would produce a straight line (linear graph). Upward opening parabola implies positive acceleration. Graph interpretation skill is essential: slope of x-t graph = velocity; curvature indicates acceleration. Memory tip: Parabolic x-t graph ⇔ constant acceleration; linear x-t graph ⇔ constant velocity. Competitive exams frequently test graph-concept correlations.

Explanation:
For a body at rest, displacement remains constant over time. The displacement-time graph is a horizontal line, parallel to time axis, indicating zero slope (velocity = 0). Option A indicates constant velocity. Option B (velocity-time zero slope) means constant velocity, not necessarily rest (could be constant non-zero velocity). Option D indicates acceleration. So C is correct.