Before using any chemical in the lab, way should one first read the material safety data sheet?

You read the SDS so you know what the hazards are working with the chemicals in the experiment and what precautionary measures should be taken. You wouldn't want to spill sensitizer or corrosive chemicals all over your hands or breath in carcinogens or chemicals that effect the central nervous system. The SDS will tell you what personal protective equipment you should use like the type of gloves, or whether or not you should work in a fume hood.

It is 4.92 e-4 sorry if i am wrong