A uniform metalli A. its speed of rotation increases.

B. its speed of rotation decreases.

C. its speed of rotation remains same.

D. its speed increases because its moment of inertia increases.

As we know moment of inertia of a rod about its perpendicular bisector is so from this formula we can say easily that if L increases then I also increases, so on heating a uniform metallic rod its length will increase so moment of inertia of rod increased from I₁ to I₂ an obviously I₂ > I₁ or .

Now also we will apply conservation of angular momentum i.e.

I₁ω₁= I₂ω₂ or so from here ω₁>ω₂ which means angular speed decreases.

Therefore option (b) is correct.