In the inversion of sucrose the rotations are +30 deg at t = 0, +10 deg at t = 40 min and -10 deg at infinite time (first order, ln2=0.693). Which statements are correct?

The rotation at t = 80 min is +0.0 deg

The rate constant is 0.0173 min^-1

The rotation at t = 120 min is -3.75 deg

The rotation at t = 80 min is +0.0 deg

The rate constant is 0.0173 min^-1

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ck154

In the inversion of sucrose the rotations are $+ 3 0^{\circ}$ at t = 0, $+ 1 0^{\circ}$ at t = 40 min and $- 1 0^{\circ}$ at infinite time (first order, $ln 2 = 0.693$ ). Which statements are correct?

r_{t} - r_{\infty}

falls from 40 to 20 in 40 min, so

t_{1/2} = 40

min and

k = 0.693/40 = 0.0173 mi n^{- 1}

. At 80 min (2 half-lives)

r = - 10 + 40/4 = + 0. 0^{\circ}

. At 120 min

r = - 10 + 40/8 = - 5. 0^{\circ}

, so the stated value is wrong.