At the center of the cloud, more weight of the gas molecules are present.
The mass or weight at the center of the cloud increases when the gas molecules group together in a molecular cloud because more gas molecules are present at the center which combines with each other leads to heavier weight of gas molecules. The combination of gas molecules make the center of the molecular cloud denser as compared to other parts of the cloud so we can conclude that increase in mass occur at the center of the cloud.
