Bad sectors

Most often a bad sector is a part of the HD platter that can no longer hold a magnetic charge. This means this area can not be marked as a 1or0 thus making it no good. Chkdsk simply marks the bad area and works around it in the future. So your hard drive actually gets a little smaller. I my experience a hd with bad sectors is a ticking time bomb. It might work fine for days or years but fallure is going to happen.

I suggest backing up all data and replaceing the hard drive.

Bad sectors are hardware problems with the actual disk media that can't be fixed by software. A bad sector isn't a problem by itself unless it actually contains data that you need, and in that case chances are you're out of luck.

Disk drives are pretty intelligent about how they handle sector problems. If they detect errors when reading from a disk sector they'll automatically retry the read over and over again until they manage to get a clean copy of the data. At that point they'll mark the problem sector as bad and then write it to a spare sector on another part of the drive. That effectively removes the bad sector from your drive. But it's something that's done by the drive itself. Software can't really do anything about this other than to request the sector from the drive and hope that the drive can deliver it.

If the drive can't successfully recover the data, the sector is marked as "pending". This is the worst case because it's data that the drive has effectively lost. Every time you try to read the data from the drive it will try to read the sector over and over again, and eventually if it can't recover the data it will return an error code. You can get rid of these sectors by writing new data to them, at which point the drive will mark the bad sector as "dead" and store the data in a spare area instead. That effectively eliminates the bad sector, but it also means that all hope of recovering the data from it is gone.

is there a solution?
if i attach a new harddisk along with old bad one will it transfer bad sectors to my new disk?

No, there really isn't a solution. If the drive has bad sectors and it can't recover the data from them, then they're just going to stay that way. Bad sectors on a drive aren't really a big problem unless (a) they contain data you need, or (b) the number of sectors is increasing as you use the drive, which suggests that your drive is degrading and might fail.

Bad sectors on one disk have nothing whatsoever to do with bad sectors on any other disks. You don't have to worry about them being "contagious".