Question

what is moment of inertia scalar or vector

Answer 1

actually its a tensor quantity but in some books it is given as scalar quantity. Tensor quantity means sometimes a parameter or a quantity behaves as scalar and sometimes it behaves as vector. Here Inertia is the property of mass

Answer 2

moment of inertia is neither a scalar nor a vector because..Moment of inertia is the product of mass and radius sq.
Where mass is a scalar and radius (displacement) is a vector quantity.