The metal having the least electrical resistance is _________.

If light falls perpendicularly on a plane mirror, what will be the angle in which it will be reflected?

Organelle that aid in storage and secretion of chemical substances is _______.

Seismograph is an instrument used to ________.

The non-metal used in the vulcanization of rubber is ____________.

The deterioration of materials by a chemical reaction with their environment is called _______. 

The rao of force acng perpendicular to the area on which it acts is known as __________. 

The lens which is thinner at the middle than the edges is __________.