Convert $2$ angstrom into picometre.

Name the instrument you would use to measure the external diameter of a ball pen refill.

To avoid the _____ error, while taking the measurements, the screw should be rotated in one direction only.

A circular scale of a screw gauge has $50$ divisions and pitch $0.5 \mathrm{mm}$. Find the diameter of the sphere (main scale reading is $2$)

The _____ of a micrometer screw gauge can be defined as the distance between its two consecutive threads, that is the distance traversed by the screw in one complete rotation of its head.

Name the instrument you would use to measure the thickness of a thin glass plate.

The _____ of a micrometer screw gauge can be defined as the ratio of the pitch to the total number of divisions on the circular scale.