A hydrogenation reaction is carried out at 500 K. If the same reaction is carried out in the presence of a catalyst at the same rate, the temperature required is 400 K. Calculate the activation energy of the reaction if the catalyst lowers the activation barrier by 20 kJ mol-1.
Answer
(C)
80 kJ mol-1
1
The number of nodal planes in a px orbital is
Answer
(A)
one
2
The following electrochemical cell has been set up.
Pt(1) | Fe3+, Fe2+ (a = 1) | Ce4+, Ce3+ (a=1) | Pt(2)
Eo (Fe3+, Fe2+) = 0.77 V; Eo (Ce4+, Ce3+) = 1.61 V
If an ammeter is connected between the two platinum electrodes, predict the direction of flow of current. Will the current increase or decrease with time?
Answer
(E)
Cerium electrode to iron electrode, decrease
2
Amongst the following identify the species with an atom in +6 oxidation state
Answer
(D)
$$Cr{O_2}C{l_2}$$
3
Copper sulphate solution (250 mL) was electrolysed using platinum anode and a copper cathode. A constant current of 2mA was passed for 16 minutes. It was found that after electrolysis the absorbance of the solution was reduced to 50% of its original value. Calculate the concentration of copper sulphate in the solution to begin with.
Answer
(C)
7.96 x 10^-5 mol L^-1
3
The electronic configuration of an element is 1s2, 2s2 2p6, 3s2 3p6 3d5, 4s1 This represents its
Answer
(B)
ground state
4
To 500 cm3 of water, 3.0 $$\times$$ 10-3 kg of acetic acid is added. If 23% of acetic acid is dissociated, what will be the depression in freezing point? Kf and density of water are 1.86 K kg-1 mol-1 and 0.997 g cm-3, respectively
Answer
(C)
0.228 K
4
The correct order of radii is
Answer
(B)
F- < O2- < N3-
5
Write down the M.O. electron distribution of O2. Specify its bond order and magnetic property.
Answer
(A)
σ2s2σ2s*2σ2p2π2p4π2p*2, Bond order=2, Paramagnetic
5
The correct order of acidic strength is
Answer
(A)
Cl2O7 > SO2 > P4O10
6
Calculate the energy required to excite one litre of hydrogen gas at 1 atm and 298 K to the first excited state of atomic hydrogen. The energy for the dissociation of H-H bond 436 kJ mol-1.
Answer
(D)
98.32 kJ
6
Amongst H2O, H2S, H2Se and H2Te, the one with the highest boiling point is
Answer
(A)
H2O because of hydrogen bonding
7
Read the following statement and explanation and answer as per the options given below
ASSERTION : The first ionization energy of Be is greater than that of B.
REASON : 2p orbital is lower in energy than 2s.
Answer
(C)
If assertion is CORRECT, but reason is INCORRECT
8
Molecular shape of SF4, CF4 and XeF4 are
Answer
(D)
different, with 1, 0 and 2 lone pairs of electrons respectively
9
The hybridisation of atomic orbitals of nitrogen in $$NO_2^+$$, $$NO_3^-$$ and $$NH_4^+$$ are
