4) What denotes by 8 in the (A46H5V8) mentioned marking system of a grinding wheel?

5) Which natural abrasive used to make grind stones?

6) Which part of surface grinding machine carriers the table in its crosswise movement?

7) What type of surface is produced by internal cylindrical grinding?

8) What is the name, if the rate at which a point on the work surface pass a point on the wheel surface?