Description : Benzene cannot undergo – (1) Substitution (2) Addition (3) Elimination (4) Oxidation
Last Answer : (3) Elimination Explanation: Benzene can not undergo Elimination reaction.
Description : Benzene cannot undergo : (1) Substitution (2) Addition (3) Elimination (4) Oxidation
Last Answer : Elimination
Description : Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?
Last Answer : Ans. Due to the presence of an electron cloud containing 6 pi electrons above and below the plane of the ring, benzene is a source of electrons. Consequently, it attracts ... . As a result, benzene undergoes electrophilic substitution reactions easily and nucleophilic substitution with difficulty.
Description : Why do aldehydes undergo nucleophilic addition reactions while esters undergo nucleophilic acyl substitution reactions? (a) The carbonyl carbon of an ester is more electrophilic than that of an aldehyde. (b) ... adds to an aldehyde, neither H− nor R− can be eliminated since they are strongly basic
Last Answer : Once the nucleophile adds to an aldehyde, neither H− nor R− can be eliminated since they are strongly basic
Description : Which statement about the carbonyl group of ketones and aldehydes is true? I. It can attract nucleophiles. II. It can attract electrophiles. III. It tends to undergo addition reactions. IV. It tends to undergo substitution reactions. (a) I and III (b) II and IV (c) I, II, and III (d) I, III, and IV
Last Answer : I, II, and III
Description : Alkyl halides undergo (a) Electrophilic substitution reactions (b) Electrophilic addition reactions (c) Nucleophilic substitution reactions (d) Nucleophilic addition reactions
Last Answer : Nucleophilic substitution reactions
Description : Which of the following statements correctly describes the general reactivity of alkynes? (a) An alkyne is an electron-rich molecule and therefore reacts as a nucleophile. (b) The σ bonds ... fail to undergo electrophilic addition reactions. (d) Alkynes are generally more reactive than alkenes.
Last Answer : Alkynes are generally more reactive than alkenes.
Description : An organic compound (A) has a molecular weight 78 and an empirical formula CH. (A) is resistant to attack by oxidizing agents but undergoes substitution and addition reactions. X-ray analysis shows that the ... suggests that compound (A) is (a) Benzene (b) Cyclohexane (c) Toluene (d) n-Hexane
Last Answer : Benzene
Description : Give reason: Alkanes undergo only substitution reactions but alkenes and alkynes undergo both substitution and addition reactions.
Last Answer : Alkenes and alkynes have double and triple bonds, which on breaking can add hydrogen atoms to satisfy the valency.
Description : Out of benzene, m–dinitrobenzene and toluene which will undergo nitration most easily and why?
Last Answer : Ans. -CH3 group is electron donating while –NO2 group is electron withdrawing. Therefore, maximum electron density will be in toluene , followed by benzene and at least in m-dinitrobenzene. Therefore, the ease of nitration decreases in the order: Toluene> benzene> m-dinitrobenzene
Last Answer : Ans. -CH3 group is electron donating while –NO2 group is electron withdrawing. Therefore, maximum electron density will be in toluene, followed by benzene and at least in m-dinitrobenzene. Therefore, the ease of nitration decreases in the order: Toluene> benzene> m-dinitrobenzene
Description : Which one of the following processes aims at producing higher yield of gaseous unsaturated hydrocarbons and aromatics like benzene & toluene? (A) Reforming (B) Pyrolysis (C) Alkylation (D) Hydrocracking
Last Answer : (A) Reforming
Description : Classify the following into saturated and unsaturated hydrocarbons – Benzene, cyclopropane, alkene and alkane, methane, ethene, Propyne, butene
Last Answer : Saturated: Alkane, cyclopropane, methane Unsaturated: Benzene, alkene, ethene, Propyne, butene
Description : Aryl benzene sulphonate (ABS) is a (A) Detergent (B) Plasticiser for unsaturated polyester (C) Starting material for the synthesis of glycerine (D) Coating ingredient for photographic film
Last Answer : (A) Detergent
Description : Which of the following compounds will not undergo azo coupling reaction with benzene diazonium chloride?
Last Answer : Which of the following compounds will not undergo azo coupling reaction with benzene diazonium chloride? ... B. Phenol C. Anisole D. Nitrobenzene
Description : What are enzymes? (a) saccharides that catalyze chemical reactions (b) unsaturated fats that catalyze chemical reactions (c) DNA molecules that catalyze chemical reactions (d) proteins that catalyze chemical reactions
Last Answer : proteins that catalyze chemical reactions
Description : Can tertiary amines undergo acetylation reactions ? Explain.
Last Answer : For an amine to undergo acetylation, it should have a replaceable hydrogen atom. Tertiary amines cannot undergo acetylation reactions because these do not have replaceable hydrogen atom.
Description : Which of the following is not correct concerning substitution and elimination reactions of alkyl halides? (a) The electrophile replaces the leaving group. (b) Compounds containing electron-donating groups bonded to an ... replaced by another atom or group in substitution reactions. (d) (a) and (b)
Last Answer : (a) and (b)
Description : Hastelloy C is a good material of construction in chemical process industry, since it is (A) Highly corrosion resistant and is readily fabricated (B) Relatively inexpensive although it can be ... most alkalis, particularly because of its copper content (D) Light and resists attack by acids
Last Answer : (D) Light and resists attack by acids
Description : Adding Cl2 to benzene in the presence of AlCl3 is an example of – (1) Elimination reaction (2) Substitution reaction (3) None of the options (4) Addition reaction
Last Answer : (2) Substitution reaction Explanation: The reaction between benzene and chlorine in the presence of a catalyst such as aluminium chloride gives Chlorobenzene. This reaction is an example of electrophilic substitution ... since one of the hydrogen atoms on the ring is replaced by a chlorine atom.
Description : Benzene reacts with concentrated HNO3 in the presence of concentrated H2SO4 to give nitrobenzene. This reaction is an example of (a) Electrophilic addition (b) Nucleophilic addition (c) Electrophilic substitution (d) Nucleophilic substitution
Last Answer : Electrophilic substitution
Description : Benzene undergoes substitution reaction more easily than addition reaction because (a) it has a cyclic structure (b) it has three double bonds (c) it has six hydrogen atoms (d) there is delocalization of electrons
Last Answer : there is delocalization of electrons
Description : Which of the following is not a correct statement about the electrophilic substitution mechanism of benzene? (a) Benzene functions as a nucleophile. (b) Formation of a carbocation intermediate is the ... hybridized carbon in the ring. (d) The addition product is a frequently observed minor product.
Last Answer : The addition product is a frequently observed minor product.
Description : Adding Cl2 to benzene in the presence of AlCl3 is an example of : (1) Elimination reaction (2) Substitution reaction (3) None of the options (4) Addition reaction
Last Answer : Substitution reaction
Description : Which of the following reactions does not produce benzene as one of the products? (a) Treating benzenediazonium chloride with H3PO2 (b) Distilling phenol with zinc dust (c) Fusing sodium benzoate with NaOH (d) Fusing sodium benzenesulfonate with NaOH
Last Answer : Fusing sodium benzenesulfonate with NaOH
Description : Which of the reactions between the following pairs of reagents proceeds by a mechanism that may be described as an electrophilic substitution? (a) Benzene + Br2/FeBr3 (b) Propene + Br2 (c) Acetone + NH2NH2 (d) Ethyl bromide + aq KOH
Last Answer : Benzene + Br2/FeBr3
Description : In condensation polymerisation as compared to addition polymerisation (A) The monomers are unsaturated compounds (B) No co-product is lost (C) The monomers contain two functional groups (D) Generally only one monomer is involved
Last Answer : (C) The monomers contain two functional groups
Description : What addition reaction will hydrocarbon undergo?
Last Answer : What is the answer ?
Description : Pick out the wrong statement. (A) DDT is manufactured by the condensation of chlorobenzene with chloral at 30°C in presence of oleum, which is a highly exothermic reaction (B) Chloral ... through the respiratory system are called fumigants (D) Benzene hexachloride is not a contact insecticide
Last Answer : (D) Benzene hexachloride is not a contact insecticide
Description : Which one of the following statements regarding a catalyst is not correct? A An enzyme is a catalyst that only binds certain substrates. B An enzyme is a protein that is a highly ... increasing the activation energy. D Catalysts do not alter the equilibrium constant for a chemical reaction.
Last Answer : C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy.
Description : BHC (Benzene hexachloride) is made by the chlorination of benzene (A) Which is an addition reaction (B) Which is a substitution reaction (C) In absolute dark (D) In presence of sunlight
Last Answer : (A) Which is an addition reaction
Description : Which of the following reactions of benzene proves the presence of three carbon-carbon double bonds in it :
Last Answer : Which of the following reactions of benzene proves the presence of three carbon-carbon double ... of concentrated nitric acid and sulphuric acid
Description : Conversion of benzene diazonium chloride to chloro benzene is an example of which of the following reactions ?
Last Answer : Conversion of benzene diazonium chloride to chloro benzene is an example of which of the following ... Friedel-Crafts acylation C. Sandmeyer D. Wurtz
Description : Assertion: Phenol is more reactive than benzene towards electrophilic reactions. Reason : The +R effect of OH group increases the electron density on
Last Answer : Assertion: Phenol is more reactive than benzene towards electrophilic reactions. Reason : The +R effect of ... D. A is incorrect but R is correct
Description : Arrange the following carboxyl compounds in increasing order of their reactivity in nucleophilic addition reactions. Explain with proper reasoning : Benzaldehyde. p-tolualdeyde, p-nitrobenzaldehyde, Acetophenone.
Last Answer : Ans. Acetophenone is a ketone while all others are aldehydes, therefore it is least reactive. In p-tolualdehyde, there is methyl group (CH3 ) at para position w.r.t. to the ... overall order of increasing reactivity : acetophenone < p-tolualdehyde < benzaldehyde < p-nitrobenzaldehyde.
Description : Which of the following characterizes the reactions of aldehydes and ketones? (a) electrophilic addition (b) electrophilic substitution (c) nucleophilic acyl substitution (d) nucleophilic addition; free radical addition
Last Answer : nucleophilic addition; free radical addition
Description : A batch reactor is suitable for (A) Achieving cent percent conversion of reactants into products (B) Large scale gaseous phase reactions (C) Liquid phase reactions (D) Obtaining uniform polymerisation products in highly exothermic reactions
Last Answer : (C) Liquid phase reactions
Description : The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are: (A) Always irreversible (B) Insensitive to temperature changes (C) Mostly irreversible (D) Highly temperature sensitive
Last Answer : (B) Insensitive to temperature changes
Description : Which of the following phases of psychological reaction to rape is characterized by fear and flashbacks? a) Heightening anxiety phase During the heightened anxiety phase, the patient demonstrates anxiety, ... the incident is put into perspective. Some patients never fully recover from rape trauma.
Last Answer : a) Heightening anxiety phase During the heightened anxiety phase, the patient demonstrates anxiety, hyperalertness, and psychosomatic reactions, in addition to fear and flashbacks.
Description : (2) amount of oxygen used for biochemical oxidation Explanation: Biochemical oxygen demand or B.O.D. is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to ... quantitative test, although it is widely used as an indication of the organic quality of water.
Last Answer : The addition of gypsum to port-land cement helps in : (1) increasing the strength of cement (2) rapid setting of cement (3) preventing rapid setting of cement (4) reduction in the cost of cement
Description : Although Diamond is Covalent, yet it has high melting point. Why?
Last Answer : Ans. All the four valencies are satisfied by carbon.
Description : Why liquids do not have definite shape although they have definite volume?
Last Answer : Ans.Because inter molecular forces are strong enough to hold the molecules but not so strong as to fix them into definite position.
Description : Although — NH2 gp is an ortho and para directing gp, nitration of aniline gives along with ortho and para, meta derivatives also.
Last Answer : Nitration is carried out with a mixture of Conc. NO3 + Conc. H2 SO4 (nitrating mix). In the presence of these acids, most of aniline gets protonated to form anilinium ion. Therefore, in the ... is m-directing and deactivating hence a mixture of all three-ortho, para and meta derivatives is formed.
Description : Suggest a reason for the large difference in the boiling points of butanol and butanal, although they have same solubility in water.
Last Answer : The b. pt. of butanol is higher than that of butanal because butanol has strong intermolecular H-bonding while butanal has weak dipole-dipole interaction. However both of them form H-bonds with water and hence are soluble.
Description : Although thermodynamically feasible, in practice, Magnesium metal is not used for the reduction of Alumina in the metallurgy of aluminium.Why?
Last Answer : Ans. : Below the temperature(1623 K) correspoinding to the point of intersection of Al 2O3 and MgO curves in Ellingham diagram, Magnesium can reduce Alumina because the ΔfG o value of Al2O3 at ... to Al. But Magnesium is much costier metal than Aluminium and hence the process will be uneconomical.
Description : Two compounds have the same composition and also have the same atoms attached to the same atoms, although with different orientations in space. These compounds are (a) Identical (b) Position isomers (c) Structural isomers (d) Stereoisomers
Last Answer : Stereoisomers
Description : During electrolysis of aqeous solution of NaCl, there are two type of anions are present Cl- and –OH, Cl- is discharged first than –OH,although it is present below Cl- in electrochemical series. Give reason.
Last Answer : Ans: During this electrolysis process Chloride ions come from NaCl, which is a strong electrolyte and ionize to large extent so concentration of chloride ions in solution will be high. ... chloride ions it is first discharged despite of its presence above than hydroxyl in electrochemical series.