i just want to ask if i can backup my iphone using mobile data?
It can be done for iPhone 12 or later, with certain conditions. Apple's support document Backup iPhone says:
Back up iPhone
On models that support 5G, your carrier may give you the option to back up iPhone using your cellular network. Go to Settings > [your name] > iCloud > iCloud Backup, then turn on or off Backup Over Cellular.
This of course depends on the size of your phone data plan, and the reliability of connection.For older iPhones- 4G or earlier - the data transfer is too slow and the connections sub-optimal for the important work of backing up your iPhone.
Otherwise, you can backup your iPhone to a computer with iTunes or for more recent Macs via the Finder.