31.

For a first order reaction at 27°C, the ratio of time required for 75% completion to 25% completion of reaction is

• 3.0

• 2.303

• 4.8

• 0.477

Which one of the following is most effective in causing the coagulation of an As₂S₃ sol?

• KCl

• AlCl₃

• MgSO₄

• K₃Fe(CN)₆

In Gattermann reaction, a diazonium group is replaced by $\underline{\mathrm{X}}$ using $\underline{\mathrm{Y}}$. $\underline{\mathrm{X}}$ and $\underline{\mathrm{Y}}$ are-

• $\underline{\mathrm{X}}$ - ${\mathrm{Cl}}^{⊝}$; $\underline{\mathrm{Y}}$ - Cu/ HCl 

• $\underline{\mathrm{X}}$ - ${\mathrm{Cl}}^{\oplus }$ ; $\underline{\mathrm{Y}}$ - CuCl₂/ HCl

• $\underline{\mathrm{X}}$ - ${\mathrm{Cl}}^{⊝}$; $\underline{\mathrm{Y}}$ - CuCl₂/ HCl

• $\underline{\mathrm{X}}$ - Cl₂ ; $\underline{\mathrm{Y}}$ - Cu₂O/ HCl

What are $\underline{\mathrm{X}}$ and $\underline{\mathrm{Y}}$ in  the following reaction sequence?

C₂H₅OH $\stackrel{{\mathrm{Cl}}_2}{\to } \underline{\mathrm{X}} \stackrel{{\mathrm{Cl}}_2}{\to } \underline{\mathrm{Y}}$

• C₂H₅Cl, CH₃CHO

• CH₃CHO, CH₃CO₂H

• CH₃CHO, CClCHO

• C₂H₅Cl, CCl₃CHO

What are $\underline{\mathrm{A}}, \underline{\mathrm{B}} \mathrm{and} \underline{\mathrm{C}}$ in the following reactions?

(I) (CH₃CO₂)₂Ca $\stackrel{∆}{\to } \underline{\mathrm{A}}$

(II) CH₃CO₂H $\underset{\mathrm{Red} \mathrm{P}}{\overset{\mathrm{HI}}{\to }} \underline{\mathrm{B}}$

(III) 2CH₃CO₂H $\stackrel{{\mathrm{P}}_4{\mathrm{O}}_{10}}{\to } \underline{\mathrm{C}}$

• $\underline{\mathrm{A}}$ - C₂H₆ ; $\underline{\mathrm{B}}$ - CH₃COCH₃ ; $\underline{\mathrm{C}}$ - (CH₃CO)₂O

• $\underline{\mathrm{A}}$ - (CH₃CO)₂O ; $\underline{\mathrm{B}}$ - C₂H₆ ; $\underline{\mathrm{}}$$\underline{\mathrm{C}}$ - CH₃COCH₃

• $\underline{\mathrm{A}}$ - CH₃COCH₃ ; $\underline{\mathrm{B}}$ - C₂H₆ ; $\underline{\mathrm{C}}$ - (CH₃CO)₂O

• $\underline{\mathrm{A}}$ - CH₃COCH₃ ; $\underline{\mathrm{B}}$ - (CH₃CO)₂O ; $\underline{\mathrm{C}}$ - C₂H₆

How many tripeptides can be prepared by linking the amino acids glycine, alanine and phenyl alanine?

• One

• Three

• Six

• Twelve

A codon has a sequence of A, and specifies a particular B that is to be incorporated into a C. What are A, B and C?

• A - 3 bases; B - amino acid; C - carbohydrate

• A - 3 acids; B - carbohydrate; C - protein

• A - 3 bases; B - protein; C - amino acid

• A - 3 bases; B - amino acid; C - protein

Parkinson's disease is linked to abnormaties in the levels of dopamine in the body. The structure of dopamine is

Consider the following reaction-

C₂H₅Cl + AgCN $\stackrel{\mathrm{EtOH}/ {\mathrm{H}}_2\mathrm{O}}{\to }$ X (major)

Which one of the following statements is true for X ?

(I) It gives propionic acid on hydrolysis.

(II) It has an ester functional group.

(III) It has a nitrogen linked to ethyl carbon.

(IV) It has a cyanide group.

• IV

• III

• II

• I

The synthesis of crotonaldehyde from acetaldehyde is an example of ........... reaction.

• nucleophilic addition

• elimination

• electrophilic addition

• nucleophilic addition-elimination