$A$ disymmetric object is one which is:

What is the number of chiral carbon atoms in $2$-chlorobutane?

Explain the following terms:
$(i)$ Plane polarised light
$(ii)$ Optical activity
$(iii)$ Chirality
$(iv)$ Chiral centre (atom)
$(v)$ Enantiomers
$(vi)$ Diastereomers
$(vii)$ Meso compounds
$(viii)$ Plane of symmetry and Achiral molecule
$(ix)$ Centre of symmetry

Which of the following is optically active?

Total number of optically active compounds from the following is $......$

$CH_3-CH(OH)-COOH$ shows