VITEEE 2018 :: Chemistry :: General questions

• Chemistry - General questions

Which one of the following has an optical isomer?

(en = ethylenediamine)

Answer:

Explanation:

Option (b) shows optical isomerism

$\left[Co(en)_{3}\right]^{3+}$

Complexes of Zn⁺⁺ cannot show optical isomerism as they are tetrahedral complexes with plane of symmetry

$\left[Co(H_{2}O)_{4}(en)\right]^{3+}$have two planes of symmetry hence it is also optically inactive.

$\left[Zn(en)_{2}\right]^{2+}$cannot show optical isomerism

Which of the following is best method for reducing 3-bromopropanal to 1 -bromopropane

Answer:

Explanation:

In Wolf-Kishner reduction  NH₂NH₂ /OH‾ is used. Br^- can be replaced by OH^-

Calculate enthalpy change for the change

8S_(g) → S_8(g), given that

H₂S₂(g) → 2H(g) + 2S(g)

                                 ΔH = 239.0 kcal mol^-1

H₂S(g) → 2H(g) + S(g)

                                 ΔH = 175.0 kcal mol^-1

Answer:

Explanation:

$\triangle H_{S-S}+2\triangle H_{H-S} = 239$

$2\triangle H_{H-S} = 175$

Hence,

$\triangle H_{S-S}=239-175=64kcal mol^{-1}$

Then, ΔH for 8S_(g) → S_8(g)  is 8 x (-64) = -512kcal

The molecular formula of diphenyl methane  

is C₁₃H₁₂. How many structural isomers are possible when one of the hydrogens is replaced by a chlorine atom?

Answer:

Explanation:

In diphenylmethane monochlorination at  following positions will produce structured isomers

For which one of the following systems at equilibrium, at constant temperature will the doubling of the volume cause a shift to the right?

Answer:

Explanation:

When volume is increased the conc. decreases & the equilibrium shifts in the direction where more moles are formed

• Chemistry - General questions