A balloon filled with air bursts when it rises up in the sky

Yes

Explanation:

balloon bursts when too much of the air is pumped into it because the inner pressure of the balloon becomes very high than the outer pressure acting on it. The air exerts pressure inside the ballon and takes it to the point where it can not stretch and it bursts.

This is because of change in pressure. The atmospheric pressure decreases as we move higher in the atmosphere. Now, as a balloon is filled near the earth's surface, the pressure inside the balloon is high. We also know that air travels from high pressure to low pressure. So, as the balloon moves higher in the atmosphere the pressure inside the balloon becomes relatively higher than outside the balloon with increasing height, so the air inside tends to move outwards to low pressure area and hence the size of the balloon keeps on increasing to the point when the material of the balloon cannot withstand the pressure and the balloon bursts.

conservation of mass

mass before something happens = mass afterwards