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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Most of the electrophilic reactions are irreversible, but not sulphonation . Why? |
Answer» Solution :Most electrophilic subsitution reactions are irreversible but sulphonation is an exception. Treatment of benzene with "oleum" (a solution of `SO_(3)` in concentrated sulphuric acid) will give the sulphonic acid, the electrophilic species being sulphur trioxide which is Lewis acid.  The sulphonic acid can be converted back by treatment with hot aqueouus acid. The reason for this reversibility is the fact that the Wheland intermediate is OVERALL neutral and therefore more STABLE than other, positively charged intermediates. Hence under forcing reaction conditions, the energy difference is PROGRESSING in either the forward or backward Wheland intermediate direction for the formation of  This makes the `SO_(3)H` a useful directing group if it is desired to carry our selective ortho- substitution of a monosubstiuted benzene possessing an ortholpara- activating group. Under normal circumstances, para - substitution would dominate, despite the statistical favouring of the ortho- positions due to steric HINDRANCE of the original SUBSTITUENTS. Intial sulphonation of para- gives a Disubstituted benzene in which both substituents direct to the same position.Subsequently directed electrophilic substitution and removal of the sulphonic acid group gives the ortho-disubstituted product. |
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| 2. |
Most of the elementary gases are obtained by chemical reaction of their compounds for example chlorine is obtained by allowing KMnO_4 to react with hydrochloric acid. Fluorine however can be obtained only by the electrolysis of a fluoride this is because |
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Answer» FLUORINE is a HIGHLY reactive gas |
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| 3. |
Most of the deodorants contain aluminimn salts because they |
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Answer» ACT as antiperspirants |
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| 4. |
Most of the copper used to make wire has been electrically refinedby depositing it from copper salts solution (divalent) on to a cathode. What is the ost of electrical energy required per kg of copper if the cost of electricity is Rs. 0.25 per kWh and the cell operates at 0.2 volt ? The electrochemical equivalent of copper is 0.00033 g/coulomb. |
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| 5. |
Most of the compounds formed by noble gases are with : |
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Answer» FLUORINE |
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| 6. |
Most of the alpha-amino acids exist as ............. |
| Answer» SOLUTION :ZWITTERIONS | |
| 7. |
Most of the amino acid have chiral centres but not in |
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Answer» PHENYL ALANINE |
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| 8. |
Most of receptors are embedded in .... |
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Answer» NERVE CELL |
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| 9. |
Which alkaline earth metal is used in treatment of cancer :- |
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Answer» Barium |
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| 11. |
Most inert among the following |
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Answer» He |
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| 13. |
Most important causative pollutant of soil may be |
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Answer» Plastics |
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| 14. |
Most hazardous metal pollutant of automobile exhaust is |
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Answer» CADMIUM |
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| 15. |
Most harmful pollutant is |
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Answer» `NO_2` |
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| 16. |
Which is the most favourable condition for the alcoholic fermentation of sugar? |
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Answer» High concentration of sugar SOLUTION, LOW temperature, PLENTY of air |
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| 17. |
Most explosive compound is : |
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Answer» `NCl_3` |
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| 18. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Draw the structures of all possible isomers of Z (show only boron-carbon framework). |
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| 19. |
Which of the following is most energetic conformation of cyclohexane? |
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Answer» CHAIR conformation |
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| 20. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Write the molecular formula of a carorane (Z) obtained by replacing two Boron by carbon atoms in closo-dodecaborane anions. |
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| 21. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Draw the structures of the possible arachano-boranes derived from X. |
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| 22. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Draw the structure of B_(2)H_(8). |
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Answer» Two centered `3E^(-)` BOND square |
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| 23. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Write the general formula of arachano-boranes. |
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| 24. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Draw the structure of B_(2)H_(6). The unusual bond present in B_(2)H_(6)is a- (a)Two centered 3e- bond square , (b)Three centered 2e- bond square ( c)Four centered 2e- bond square , (d)Four centered 4e- bond square {:(B_(2)O_(3),"acidic","basic","amphoteric","neutral"),(Al_(2)O_(3),"acidic","basic","amphoteric","neutral"),(Tl_(2)O_(3),"acidic","basic","amphoteric","neutral"):} |
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| 25. |
Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of Na and Mg are distinctly alkaline, while oxides of N and S are distinctly acidic. Draw the structure of Y. |
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| 26. |
Most electropositive halogen is: |
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Answer» F |
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| 27. |
Most efficient and suitable dust removal equipment for removal of flyash from flue gas in a thermal power plant is : |
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Answer» GRAVITY SETTLING chamber |
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| 28. |
Most effective ion to coagulate a negative sol is : |
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Answer» `PO_(4)^(3-)` |
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| 29. |
Most easily liquefiable gas is ……………. . |
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Answer» Ar |
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| 32. |
Most crystals show good cleavage because their atoms, ions and molecules are: |
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Answer» WEAKLY BONDED TOGETHER |
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| 34. |
Most common reactions of benzene (aromatic hydrocarbon ) and its derivatives are |
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Answer» ELECTROPHILIC addition reactions |
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| 36. |
Most common emulsifier for vegetable oil, water emulsion is --- |
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Answer» CARBON powder |
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| 37. |
Most basic compound is |
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Answer» `C_(6)H_(5)NH_(2)` |
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| 38. |
Most basic among the following is |
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Answer» BENZYL AMINE |
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| 39. |
The most basic among the following compounds is: |
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Answer»
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| 40. |
Most and least abundant inert gases in atmosphere interms of percentage by volume are respectively |
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Answer» AR, He |
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| 42. |
Most adundantmetal in the earth crust is |
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Answer» Na |
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| 44. |
Most acidic oxide is |
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Answer» <P>`Na_(2)O` |
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| 46. |
Most abundant transition element is |
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Answer» FE |
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| 47. |
Most abundant transition element is : |
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Answer» Fe |
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| 50. |
Most abundant metal on the surface of earth is: |
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Answer» iron |
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