Basics of Organic Chemistry (GOC)

JEE Chemistry · 87 questions · Page 1 of 9 · Click an option or "Show Solution" to reveal answer

Which technique among the following, is most appropriate in separation of a mixture of

100 \,\mathrm{mg}

p

-nitrophenol and picric acid ?

A Steam distillation

B 2-5 ft long column of silica gel

C Sublimation

D Preparative TLC (Thin Layer Chromatography)

Correct Answer

Option D

Solution

Thin layer chromatography is a technique used to isolate non-volatile mixtures.

Hence, mixture of p-nitrophenol and Picric acid is separated by TLC.

Which of these factors does not govern the stability of a conformation in acyclic compounds?

A Angle strain

B Torsional strain

C Electrostatic forces of interaction

D Steric interactions

Correct Answer

Option A

Solution

Angle strain is not present in acyclic compounds.

Which of the following compounds will show the maximum 'enol' content?

A CH3COCH3

B CH3COCH2COCH3

C CH3COCH2COOC2H5

D CH3COCH2CONH2

Correct Answer

Option B

Solution

Hydrogen removed from the $\alpha$ carbon should be acidic in nature because ehen hydrogen is more acidic then enol formation is easy.

Which amongst the following is the strongest acid ?

A CHBr3

B CHI3

C CH(CN)3

D CHCl3

Correct Answer

Option C

Solution

Among those $-$ CN has highest $-$ M and $-$ I effect.

So after losing proton (H+) anion become more stable.

So, CH(CN)3 has the highest tendency to donate proton that is why it is most acidic.

Due to the presence of an unpaired electron, free radicals are:

A Chemically reactive

B Chemically inactive

C Anions

D Cations

Correct Answer

Option A

Solution

Free radicals are electrically neutral, unstable and very reactive on account of the presence of odd electrons.

In chromatography, which of the following statements is incorrect for Rf ?

A Rf value depends on the type of chromatography.

B Higher Rf value means higher adsorption.

C Rf value is dependent on the mobile phase.

D The value of Rf can not be more than one.

Correct Answer

Option B

Solution

Rf =

{x \over y}

x

= Distance moved by the substance from baseline

y

= Distance moved by the solvent from baseline Option A : Correct.

The Rf value can depend on the type of chromatography being used because different methods can use different stationary and mobile phases, which can influence how far a substance travels.

Option B : Incorrect.

The Rf value is actually inversely related to adsorption.

A higher Rf value indicates that the substance is less strongly adsorbed to the stationary phase, and therefore moves further along with the mobile phase.

Option C : Correct.

The nature of the mobile phase can greatly influence the Rf value.

The more compatible the substance is with the mobile phase, the further it will travel, leading to a higher Rf value.

Option D : Correct.

By definition, the Rf value cannot exceed one, as a substance cannot travel further than the solvent.

So, Option B is incorrect for the Rf value in chromatography.

The correct decreasing order for acid strength is :

A NO2CH2COOH > FCH2COOH > CNCH2COOH > ClCH2COOH

B FCH2COOH > NCCH2COOH > NO2CH2COOH > ClCH2COOH

C CNCH2COOH > O2NCH2COOH > FCH2COOH > ClCH2COOH

D NO2CH2COOH > NCCH2COOH > FCH2COOH > ClCH2COOH

Correct Answer

Option D

Solution

After releasing proton (H+) the more stable anion is more acidic nature.

The 4 anions are $\to$ Here $-$ NO2, $-$ CN, $-$ Cl, $-$ F all of them have $-$ I effective and all have same distance from the anion ( $-$ O $-$ ).

So depending on which one have more power $-$ I effect will be more stable.

Acidic nature $\propto$ $-$ I power.

$-$ I power order : $-$ NO2 > $-$ C $\equiv$ N > $-$ F > $-$ Cl So, acidic strength order $\to$ NO2 $-$ CH2 $-$ COOH > NC $-$ CH2 $-$ COOH > F $-$ CH2 $-$ COOH > Cl $-$ CH2 $-$ COOH

The principle of column chromatography is :

A Gravitational force.

B Capillary action.

C Differential adsorption of the substances on the solid phase.

D Differential absorption of the substances on the solid phase.

Correct Answer

Option C

Solution

The principle of column chromatography is based on the differential adsorption of substances on the solid phase.

This means that different substances in a mixture will interact with the solid stationary phase to different extents.

Some substances will adsorb more strongly to the solid phase and will therefore move more slowly through the column, while others will adsorb less strongly and will therefore move more quickly.

This differential adsorption allows for the separation of the substances in the mixture.

So, the correct answer is : Option C : Differential adsorption of the substances on the solid phase.

If dichloromethane (DCM) and water (H2O) are used for differential extraction, which one of the following statements is correct ?

A DCM and H2O would stay as upper and lower layer respectively in the separating funnel (S.F.)

B DCM and H2O will make turbid/colloidal mixture

C DCM and H2O would stay as lower and upper layer respectively in the separating funnel(S.F).

D DCM and H2O will be miscible clearly

Correct Answer

Option C

Solution

Density of DCM = 1.39 and density of H2O = 1.0.

Dichloromethane (DCM) is a denser solvent than water.

Therefore, when a mixture of DCM and water is allowed to settle in a separating funnel, the DCM forms the lower layer due to its higher density, while the water forms the upper layer.

The two solvents are immiscible, meaning they do not mix and form two distinct layers.

So, the correct answer is : Option C : DCM and H2O would stay as lower and upper layer respectively in the separating funnel(S.F).

Q10

Glycerol is separated in soap industries by :

A Fractional distillation

B Distillation under reduced pressure

C Differential extraction

D Steam distillation

Correct Answer

Option B

Solution

Glycerol is separated in soap industries by distillation under reduced pressure.

Ready for a full JEE mock test? Timed · full syllabus · detailed solutions after submission

Take a Mock Test →