Question

what is quantum mechanics?

Answer 1

it is a quatum theory and a funda mental theory of physics..
help me to make brainlist

Answer 2

basically quantum mechanics is the branch of physics relating to the very small  (sometimes, on the not-so-small scale!). Some "large" things (super-fluids, for example, and Bose-Einstein condensates) are "tiny objects writ large", where the entire entity acts according to quantum rules.  

The most important (and, usually, troubling) result of quantum mechanics is that one can only ever calculate _probabilities_ for events, rather than certainties.

Quantum mechanics can basically be thought of as a set of laws that are used to predict the behavior of very tiny particles.

hope this helps