A man lifts 50 kg of mass up to a height of 2 m. What is the work done by the man? (Assume g = 10m/s²⁾

We know, work done on an object is equal to the change in its energy.

The energy possessed by an object due to its position relative to other objects is the potential energy. 

When a man lifts 50 kg of mass up to a height of 2 m, the work done is stored as potential energy.

So, the potential energy will be counted here:

Work done = potential energy  
$\Rightarrow$W = m x g x h
Where m is the mass of the object, g is the acceleration due to gravity, h is the height of the object.
Given:
Mass, m = 50 kg
Height, h = 2 m

g = 10 m/s²
Work done, 

W = 50 x 2 x 10 = 1000 J
The work done by the man is 1000J.