When i write a disc it is asking for the speed such as 18x,42x?Why?

what is use of that resort?Suppose if i write a CD near 52x speed will it read the contents at that speed or it is Hardware Dependent?

When i write a disc it is asking for the speed such as 18x,42x?Why?

It asks cause your compact disc writer supports writing at these sppeds. The faster you write, quickly the disc will be written. But sometimes CDs go useless if we write at really high speeds and the burning process fail. So write at moderate speeds.

Your drive will read the data regardless of the speed at which you adjectives the CD. The reading is other a different specification and your drive will read all the CDs at matching speed, if there is nil wrong with the disc itself.
This is the speed at which the system writes the data on the disc. 1X = 150KB/s.



Its a better option to write CDs at a max of 24x. If you write CDs at 52x they never bring write at that speed bcoz it require very soaring quality disk not the local ones. And also your system should be satisfactory powerful. And there is individual max of 2 min difference in time if you write at 24x and 52x but at 24x the disk rotates at much slighter speed and that gurante a better quality writing.
Depending on the type of medium (CD brand), burning it at a high speed will sometimes build unreliable Cd's. If you slow down the burner, it will make the indentations on the CD-r a bit better and will give you a more reliable disk. If I take home a CD for someone, I burn it at the max speed, if I form one for myself, I use the slowest speed. This is just a opinion of mine, but I have see a difference in talent depending on speed. And to answer the last segment of your question: No. If you burn a compact disc at 52x it will not necessarily be read at that speed. Like you said, it is hardware dependent, so it'll be read at the CD-Roms speed limitations.