(ΔH – ΔU) for the formation of carbon monoxide (CO) from its elements at 298 K is (R = 8.314 JK–1 mol–1)
- 1238.78 J/mol
- 2477.57 J/mol
- –2477.57 J/mol
- –1238.78 J/mol
Bakelite is obtained from phenol by reaction with
Which of the following is fully fluorinated polymer?
The decreasing order of nucleophilicity among the nucleophiles is
- 3, 2, 1, 4
- 4, 3, 2, 1
- 2, 3, 1, 4
- 1, 2, 3, 4
Due to the presence of an unpaired electron, free radicals are
- chemically inactive
- chemically reactive
Which of the following is the correct order of decreasing SN2 reactivity? (X is a halogen)
- RCH2X > R2CHX > R3CX
- R3CX > R2CHX > RCH2X
- R2CHX > R3CX > RCH2X
- RCHX > R3CX > R2CHX
For which of the following parameters the structural isomers C2H5OH and CH3OCH3 would be expected to have the same values? (Assume ideal behavior)
- Boiling points
- Vapor pressure at the same temperature
- Gaseous densities at the same temperature and pressure
- Heat of vaporization
The coordination number and the oxidation state of the element E in the complex [E(en)2(C2O4)]NO2 (where (en) is ethylene diamine) are, respectively
- 6 and 3
- 4 and 2
- 4 and 3
- 6 and 2
Which of the following facts about the complex [Cr(NH3)6]Cl3 is wrong?
- The complex is paramagnetic.
- The complex gives white precipitate with silver nitrate solution.
- The complex is an outer orbital complex.
- The complex involves d2sp3 hybridisation and is octahedral in shape.
The coordination number of a central metal atom in a complex is determined by
- the number of only anionic ligands bonded to the metal ion
- the number of ligands around a metal ion bonded by sigma and pi bonds both
- the number of ligands around a metal ion bonded by pi bonds
- the number of ligands around a metal ion bonded by sigma bonds
The value of the ‘spin only’ magnetic moment for one of the following configurations is 2.84 BM. The correct one is
- d5 (in strong ligand field)
- d3 (in weak as well as in strong fields)
- d4 (in weak ligand field)
- d4 (in strong ligand field)
The type of isomerism present in nitropentamine chromium (III) chloride is
In the coordination compound, K4[Ni(CN)4], the oxidation state of nickel is
Which one of the following has largest number of isomers? (R = alkyl group, en = ethylenediamine)
Larger number of oxidation states are exhibited by the actinoids than those by the lanthanoids, the main reason being
- Lesser energy difference between 5f and 6d than between 4f and 5d orbitals
- More energy difference between 5f and 6d than between 4f and 5d orbitals
- More reactive nature of the actinoids than the lanthanoids
- 4f orbitals more diffused than the 5f orbitals
The lanthanide contraction is responsible for the fact that
- Zr and Hf have about the same radius
- Zr and Y have about the same radius
- Zr and Zn have the same oxidation state
- Zr and Nb have similar oxidation state
A reduction in atomic size with increase in atomic number is a characteristic of elements of
- radioactive series
- d block
- high atomic masses
- f block
The number of d electrons retained in Fe2+ (At. no. Fe = 26) ions is
A metal M readily forms its sulphate MSO4 which is water-soluble. It forms its oxide MO which becomes inert on heating. It forms an insoluble hydroxide M(OH)2 which is soluble in NaOH solution. Then M is
One mole of magnesium nitride on the reaction with an excess of water gives
- one mole of ammonia
- two moles of nitric acid
- one mole of nitric acid
- two moles of ammonia
During the process of electrolytic refining of copper, some metals present as impurity settle as 'anode mud'. These are
- Ag and Au
- Sn and Ag
- Fe and Ni
- Pb and Zn
Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides?
- MgO < K2O < Al2O3 < Na2O
- K2O < Na2O < Al2O3 < MgO
- Na2O < K2O < MgO < Al2O3
- Al2O3 < MgO < Na2O < K2O
According to the periodic law of elements, the variation in properties of elements is related to their
- atomic masses
- atomic numbers
- nuclear masses
- nuclear neutron-proton number ratios
The set representing the correct order of ionic radius is
- Li+ > Na+ > Mg2+ > Be2+
- Na+ > Li+ > Mg2+ > Be2+
- Li+ > Be2+ > Na+ > Mg2+
- Mg2+ > Be2+ > Li+ > Na+
Which one of the following characteristics is not correct for physical adsorption?
- Both enthalpy and entropy of adsorption are negative.
- Adsorption is spontaneous.
- Adsorption increases with increase in temperature.
- Adsorption on solids is reversible.
3 g of activated charcoal was added to 50 mL of acetic acid solution (0.06 N) in a flask. After an hour it was filtered and the strength of the filtrate was found to be 0.042 N. The amount of acetic acid adsorbed (per gram of charcoal) is:
- 54 mg
- 42 mg
- 36 mg
- 18 mg
Which of the following statement is incorrect regarding physissorptions?
- It occurs because of van der Waal's forces.
- More easily liquiefiable gases are adsorbed readily.
- Enthalpy of adsorption (ΔHadsorption) is low and positive.
- Under high pressure it results into multi molecular layer on adsorbent surface.
In Langmuir’s mode of adsorption of a gas on a solid surface
- the adsorption at a single site on the surface may involve multiple molecules at the same time.
- the mass of gas striking a given area of surface is independent of the pressure of the gas.
- the mass of gas striking a given area of surface is proportional to the pressure of the gas.
- the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered.
The disperse phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively. Which of the following statements is NOT correct?
- Coagulation in both sols can be brought about by electrophoresis.
- Sodium sulphate solution causes coagulation in both sols.
- Mixing of the sols has no effect.
- Magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol.
In conversion of limestone to lime,
CaCO3(s) → CaO(s) + CO2(g)
The values of ΔH° and ΔS° are +179.1 kJ/mol and 160.2 J/K respectively at 298 K and 1 bar. Assuming that ΔH° and ΔS° do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is
- 1200 K
- 1118 K
- 1008 K
- 845 K
Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 J K–1 mol–1, respectively. For the reaction, 1/2 X2 + 3/2 Y2 → XY3, ΔH = –30 kJ, to be at equilibrium, the temperature will be
- 500 K
- 750 K
- 1000 K
- 1250 K
The heat required to raise the temperature of 1 mole substance by 1°C is called
- Thermal capacity
- Molar heat capacity
- Specific heat
- None of these
For a first order reaction, (A) → products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is
- 3.47 x 10-5 M/min
- 1.73 x 10-4 M/min
- 1.73 x 10-5 M/min
- 3.47 x 10-4 M/min
For the non-stoichiometric reaction 2A + B → C + D, the following kinetic data were obtained in three separate experiments, all at 298 K.
The rate law for the formation of C is
- dc/dt = k[A]2[B]
- dc/dt = k[A]
- dc/dt = k[A][B]
- dc/dt = k[A][B]2
A reaction involving two different reactants can never be
- unimolecular reaction
- bimolecular reaction
- second order reaction
- first order reaction
The rate of a chemical reaction doubles for every 10ºC rise of temperature. If the temperature is raised by 50ºC, the rate of the reaction increases by about
- 10 times
- 24 times
- 32 times
- 64 times
The following mechanism has been proposed for the reaction of NO with Br2 to form NOBr.
NO(g) + Br2(g) ↔ NOBr2(g)
NOBr2(g) + NO(g) → 2NOBr(g)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is
The half-life of a radioisotope is four hours. If the initial mass of the isotope was 200 g, the mass remaining after 24 hours undecayed is
- 1.042 g
- 2.084 g
- 3.125 g
- 4.167 g
A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will be
- remain unchanged
- increased by a factor of 4
The half life of a radioactive isotope is three hours. If the initial mass of the isotope were 256 g, the mass of it remaining undecayed after 18 hours would be
- 16.0 g
- 12.0 g
- 8.0 g
- 4.0 g
Conductivity (unit Siemen’s S) is directly proportional to area of the vessel and the concentration of the solution in it and is inversely proportional to the length of the vessel then the unit of the constant of proportionality is
- S2 m2 mol-2
- S-2 m2 mol
- S m mol-1
- S m2 mol-1
In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to
- remove adsorbed oxygen from electrode surface
- produce high purity water
- generate heat
- create potential difference between the two electrodes
Which of the following is a redox reaction?
- NaCl + KNO3 → NaNO3 + KCl
- Mg(OH)2 + 2NH4Cl → MgCl2 + 2NH4OH
- CaC2O4 + 2HCl → CaCl2 + H2C2O4
- 2Zn + 2AgCN → 2Ag + Zn(CN)2
Freezing point of an aqueous solution is (-0.186)°C. Elevation of boiling point of the same solution is Kb = 0.512 °C, Kf = 1.86 °C, find the increase in boiling point.
- 0.186 °C
- 0.092 °C
- 0.0512 °C
- 0.2372 °C
The solubility product of a salt having general formula MX2, in water is 4 × 10–12. The concentration of M2+ ions in the aqueous solution of the salt is
- 1.6 × 10–4 M
- 1.0 × 10–4 M
- 2.0 × 10–6 M
- 4.0 × 10–10 M
The correct relationship between free energy change in a reaction and the corresponding equilibrium constant Kc is
- ΔG° = RT ln Kc
- -ΔG = RT ln Kc
- -ΔG = RT ln Kc
- -ΔG° = RT ln Kc
Among the following acids which has the lowest pKa value?
Solubility product of silver bromide is 5.0x10-13. The quantity of potassium bromide (molar mass taken as 120 g mol–1) to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is
- 6.2 x 10-5 g
- 5.0 x 10-8 g
- 1.2 x 10-9 g
- 1.2 x 10-10 g
A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapour pressure of propyl alcohol is 200 nm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm) at the same temperature will be
If α is the degree of dissociation of Na2SO4, the vant Hoff’s factor (i) used for calculating the molecular mass is
- 1 + 2α
- 1 - α
- 1 + α
- 1 - 2α