Q. 80 g of impure sugar when dissolved in a litre of water given an optical rotation of$9.9{^\circ}$, when placed in a tube of length 20 cm. If the specific rotation of sugar is $66{^\circ}$, then concentration of sugar solution will be
A) $80\ gL^{- 1}$
B) $75\ gL^{- 1}$
C) $65\ gL^{- 1}$
D) $50\ gL^{- 1}$
Explanation
(b) Here, $\theta = 9.9{^\circ},\ l = 20\ cm = 0.2m,\ s = 66{^\circ}$
$c = ?c = \frac{\theta}{ls} = \frac{9.9}{2 \times 66} = 0.075$g $cc^{- 1}$
$= 75$g$L^{- 1}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.