Introduction:
The distance between the Earth and the Moon is given as 3.8 × 10^5 km. We are asked to determine the point where the intensity of gravitational force is zero, given that the mass of the Earth is 81 times that of the Moon.

Understanding the Problem:
To solve this problem, we need to understand the concept of gravitational force and how it varies with distance. Gravitational force is the attractive force between two objects with mass. It is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Calculating the Point of Zero Gravitational Intensity:
To find the point where the intensity of gravitational force is zero, we can set up an equation using the concept of gravitational force and solve for the distance.

Let's assume the distance between the Earth and the point where the gravitational intensity is zero as 'd'. Given that the mass of the Earth is 81 times that of the Moon, we can express their masses as follows:

Mass of Earth = 81 × Mass of Moon

Using the equation of gravitational force:

F = G × (Mass of Earth) × (Mass of Moon) / (Distance)^2

Since we want to find the point where the intensity of gravitational force is zero, we can set F = 0:

0 = G × (Mass of Earth) × (Mass of Moon) / (d)^2

Simplifying the equation, we have:

0 = 81 × G × (Mass of Moon) × (Mass of Moon) / (d)^2

Solving for 'd', we get:

d^2 = (81 × G × (Mass of Moon)^2) / 0

But division by zero is undefined, which means that the intensity of gravitational force cannot be zero for any finite distance. Therefore, there is no point where the intensity of gravitational force is zero between the Earth and the Moon.

Conclusion:
In conclusion, there is no point between the Earth and the Moon where the intensity of gravitational force is zero. The gravitational force is always present, and its intensity depends on the masses of the objects and the distance between them.