To find out M, we can use the formula:

M = W/t

Where:
M = mass (in kg)
W = weight (in N)
t = time (in hours)

First, we need to calculate the weight of the object at a height of 25 meters.

Weight = mass x gravity

Weight = 120,000 kg x 9.81 m/s^2 (gravity)
Weight = 1,176,000 N

Now, we need to take into consideration that the object is lifted to a height of 25 meters in 1 hour, which means the work done is the same as the change in potential energy.

Work = change in potential energy
Work = Mgh

Where:
M = mass (in kg)
g = acceleration due to gravity (9.81 m/s^2)
h = height (in meters)

So, we have:
1,176,000 N = M x 9.81 m/s^2 x 25 m

Solving for M:
M = 1,176,000 N / (9.81 m/s^2 x 25 m)
M = 1,176,000 N / 245.25
M ≈ 4800 kg

Therefore, the mass of the object is approximately 4800 kg.