October 2012
16 posts
4 tags
Question on Quantum Numbers
How many electrons with azimuthal quantum number, l = 3 are present in an atom having atomic number 54?
4 tags
Question on Atomic Weight
A mono atomic ion has the same atomic number and same atomic weight as its neutral atom. Is this statement true or false?
4 tags
Question on Addition Reaction
When but-3-en-2-ol reacts with aq. HBr, how many products are formed and what are they?
3 tags
Question on Nucleophilic Strength
Among CH3-, NH2-, OH- and F- which one is the best Nucleophile?
4 tags
Question on Photochemical Bromination
What is the relative amounts of 1-bromopropane and 2-bromopropane obtained from the photochemical bromination of propane, if the relative reactivity of 1° : 2° : 3° Hydrogens to photochemical bromination is 1 : 82 : 1600?
4 tags
Question on Unsaturation
The Molecular formula of an organic compound is C10H16 and takes 2 moles of hydrogen per mole of it. How many rings are likely to be present in its structure?
4 tags
Question on Photochemical Chlorination
Isopentane, (CH3)2CH.CH2.CH3 can form four isomeric monochloro derivatives on photochemical Chlorination. How many of these are optically active?
3 tags
Question on Nitrogen Oxides
Which oxide of Nitrogen is produced on heating a mixture of ammonium sulphate and sodium nitrate?
3 tags
Question on Gaseous State
A gas is heated in such a way that its pressure and volume both becomes double. Then by decreasing temperature, some of the molecules of the air have been taken in container to maintain the doubled volume and pressure. Assuming one-fourth of initial number of moles has been taken in for the purpose, by what fraction the temperature must have been raised finally of initial absolute temperature?
4 tags
Question on Dehydration
What does Orthophosphoric Acid give on strong heating?
4 tags
Question on Nodal Planes
How many nodal planes are present in a px orbital?
3 tags
Question on Gaseous State
If the Compressibility Factor of a gas is less than unity at STP, will the molar volume of the gas be greater or lesser than 22.4L at STP?
4 tags
Question on pH
A weak base BOH reacts with 0.1M HCl. The dissociation constant of BOH is 10–6. When 50 ml of 0.1N BOH reacts with HCl, what will the pH of the solution be at the neutralization point of the reaction?
4 tags
Question on Chemical Kinetics
If 10–5% reactant molecules cross over the barrier in transition state at 298K, what is the activation barrier needed to cross the transition state?
3 tags
Question on Qualitative Analysis
Can Tollen’s Reagent be used to distinguish between methanoic and ethanoic acids?
4 tags
Question on Redox Reaction
1 mole of hydrazine, N2H4 reacts with one mole of selenic acid, H2SeO3, the latter is reduced to selenium. What is hydrazine converted into? Is it N2 or NH3?
September 2012
10 posts
2 tags
Question on Organic Reaction
An Organic Compound A of molecular formula C4H10O3 reacts with excess hydrogen bromide to give ethylene dibromide as the only product. What is the name of A?
5 tags
Question on Nucleophilic Substitution Reaction
Iodide ion is a good nucleophile as well as a good leaving group in nucleophilic substitution reactions. Is this statement true or false?
3 tags
Question on Electrophilic Aromatic Substitution
The following two methods can be used to convert benzene into ethylbenzene;
1. Reacting benzene with ethyl benzene and aluminium chloride (Friedel Craft’s Alkylation)
2. Reacting benzene with acetyl chloride and aluminium chloride to produce methyl phenyl ketone (Friedel Craft’s Acylation) followed by Clemmensen’s Reduction
Which out of the above two is the best suited method...
3 tags
Question on Ring Opening
Cyclohexane does not undergo ring opening compared to cyclopropane molecule during reactions. Why?
4 tags
A 10.0g mixture containing butane and but-1-ene reacts with 8.0g of bromine in carbon tetrachloride. What is the percentage composition of the mixture?
3 tags
Question on Addition Reaction
What is the name of the product formed when isobutene is treated with bromine water?
4 tags
An Organic Compound of molecular formula C4H9Cl on treatment with alcoholic KOH gives three isomeric alkenes. What is the name of the organic compound?
3 tags
Stability of Carbocation
What are the ways by which a tertiary butyl carbocation will be stabilized?
3 tags
Question on Dipole Moment
p-nitro aniline has a dipole moment greater than the sum of dipole moments of aniline and nitro benzene. Why?
4 tags
Question on Organic Conversion
How will you convert but-1-yne into pentan-2-one in not more than 3 steps?
August 2012
8 posts
4 tags
Question on Atomic Structure
The azimuthal quantum number cannot have negative values. Is this statement true or false?
4 tags
Question on Aromatic Substitution
In the following reaction, which of the two products will be the major product? Why?
3 tags
Question on Dipole Moment
Which of the following compound has a greater dipole moment?
5 tags
Question on Optical Activity
What is the IUPAC name of the simplest alkane (alkane with lowest molecular weight) which is optically active?
4 tags
Question on Grignard Reagent
What does Phenyl Magnesium bromide give when it reacts with iso-propyl alcohol?
3 tags
Question on Thermochemistry
What is the change in internal energy, DE, for a system that does 70 Joules of work as it absorbs 45 Joules of heat?
4 tags
Question on Electrochemistry
The standard reduction potential for Cu2+/Cu is +0.34 V.
What will the reduction potential for the above couple be at pH = 14?
Ksp [Cu(OH)2] = 1.0 * 10–19
3 tags
Question on Functional Group Interconversion
How will you convert Toluene into 3-phenylpropan-1-ol?
July 2012
33 posts
4 tags
Gingerol
Gingerol is the chief constituent of ginger oil. It is being extracted from the rhizome of the ginger plant Zingiber officinale. Ginerol and its dehydrated derivative, Shogaol are the primary biologically active compounds extracted from ginger. Gingerol is chemically similar to Capsaicin, the substance responsible for the spiciness in chillies. Physically, Gingerol is found as an yellow oil and...
3 tags
Question on Ionic Equilibrium
What is the degree of hydrolysis of 0.1M solution of sodium acetate in water at 25°C, given that Ka for CH3COOH is 1.8 * 10–5 and Kw of H2O is 1 * 10–14?
4 tags
Question on Structural Identification
Two compounds A and B, have the same molecular formula C6H10. Both the compounds decolourise Br2 in CCl4. Compound A gives a precipitate when treated with silver nitrate in ammonia, while B does not. A gives n-hexane when treated with excess of H2/Pd. When treated with excess of H2/Pd, B gives a product with formula C6H12. When A is oxidised with hot alkaline KMnO4 and the resulting solution...
4 tags
Question on Photochemical Chlorination
A saturated hydrocarbon (A) burns in oxygen to give carbon dioxide and water. Approximately twice as much CO2 as H2O (by weight) is produced by this combustion, the actual factor being 2.03. Photochemical chlorination of the (A) by 2.0 equivalents of chlorine gives a mixture of mono-, di- and trichloro compounds, along with small amounts of higher chlorination products. Only one monochloro isomer...
4 tags
Question on Isomerism
Two isomeric compounds (A) and (B), C10H12O don’t have –OH group and discharge colour of bromine water. Each is vigorously oxidised to 4-methoxy benzoic acid. Ozonolysis of (A) and (B) give the same product. Which type of isomerism is present in (A) and (B)?
3 tags
Question on Equilibrium Constant
All acid-base reactions do not go to completion. Reaction between a strong acid and a strong base is considered to be almost complete as the concentrations of the reactants are negligibly smaller compared to that of the products. When Naoh is titrated against HNO3 the end point occurs when the equivalents of the acid equal the equivalents of the base and the pH of the resulting solution becomes...
3 tags
Question on Gas Pressure
Equal weights of ethane and hydrogen are mixed in an empty container at 25°C. What is the fraction of the total pressure exerted by hydrogen in the mixture?
3 tags
Question on Stoichiometry
A sample of AgCl was reacted to recover pure silver.
Mass of the beaker = 29.10 g
Mass of the beaker with AgCl = 39.74 g
Mass of Ag recovered = 8.00 g
Assuming that all of the silver was recovered in the process, what mass of chlorine would have been combined with 1.00 g of silver?
3 tags
Question on Qualitative Analysis
When a salt is heated with dil. H2SO4 in the presence of little KMnO4, the pink colour of KMnO4, is discharged. Which out of (a) carbonate ion and (b) sulphite ion is the possible anion in the salt?
4 tags
Question on Hydration of Alkenes
Hydration of 3-phenyl-1-butene in dil. H2SO4 is not satisfactory method for preparing 3-phenyl-2-butanol because 2-phenyl-2-butanol is obtained instead. Why?
3 tags
Question on Isomerism
How many isomers are possible for the compound with molecular formula C2BrClFI?
4 tags
Question on Coordination Compounds
Why is [Ni(CN)4]2– diamagnetic and [NiCl4]2– paramagnetic?
4 tags
Question on Hardness of Water
In an experiment, 100 mL of tap water is taken from 1000 mL of its stock solution and boiled till the volume becomes 3/4th the original volume. The precipitate dissolved in 1 mL of 0.1M HCl solution. In another experiment, 100mL of same sample of tap water is boiled with 29 mL of 0.1N Na2CO3 solution, the resulting solution cooled and insoluble material removed by filtration....
3 tags
Question on Functional Group Interconversion
What are the reagents A and B in the following reaction?
Answer:
A is Mg / dry ether
B is D2O
3 tags
Question on Nucleophilic Substitution Reaction
The reaction between CH3I and OH- produces CH3OH and I-, while the reaction between CF3I and OH- produced CHF3 and IO-. Why?
Answer:
It is due to the difference in polarization of the C - I bond in both the starting materials.
4 tags
Question on Isomers
How will you distinguish between Maleic Acid and Fumaric Acid?
Answers:
There are many ways to distinfuish between the two acids. One way is to heat the acids in presence of a mineral acid. Maleic Acid will form a cyclic anhydride while Fumaric Acid will not.
