Is the range of the projectile dependent or independent of the projectile's mass? Explain.

It's true that force of gravity is different on different objects and is directly proportional to its mass.

For objects near the surface of Earth, the magnitude of gravitational pull is
F = mg
where m is the mass of the object and g is a constant the value of which varies from place to place. Its average value on the surface of the earth is 9.81 metres per second. And this value decreases on moving away from the surface in either directions, inwards or outwards.

Though the magnitude of earth's gravitational pull varies from object to object(depending on its mass), the acceleration produced due to this gravitational pull is constant (of course near earth's surface). So when you drop two objects of different masses from the same height, they reach the ground at the same time (neglect air resistance).

Any projectile motion is just a combination of vertical and horizontal motion. The vertical motion is controlled by the gravity because it acts in vertical direction only, no matter in what direction the projectile is moving. And, the acceleration produced due to gravity is independent of the object's mass. So, the vertical motion is independent of the mass.

The horizontal motion of a projectile is very simple. No horizontal force acts on a projectile. And so its horizontal velocity remains constant. And the range is dependent on time of flight and horizontal velocity. Time of flight being dependent on the vertical motion.

So.. We now know that mass doesn't matter for time of flight or range. And, whenever you come across a problem related to projectile motion, just break the projectile motion into horizontal and vertical motions. And deal with it like you do with motion in one direction. Makes things easier, much easier.

Hope I can be of any assistance happy new year

Gas will most likely  fill the container