The percentage of an element M is 53 in its oxide of molecular formula M2O3. Its atomic mass is about
45
9
27
36
The electronic configuration of the element with maximum electron affinity is
1s2, 2s2,2p3
1s2, 2s2,2p5
1s2, 2s2,2p6, 3s2, 3p5
1s2, 2s2,2p6, 3s2, 3p3
The incorrect statement/s among the following is/are
I. NCl5, does not exist while PCl5, does.
II. Lead prefers to form tetravalent compounds.
III. The three C-O bonds are not equal in the carbonate ion.
IV. Both O+2 and NO are paramagentic
I, III and IV
I and IV
II and III
I and III
The first ionisation energy of oxygen is less than that of nitrogen. Which of the following is the correct reason for this observation?
Lesser effective nuclear charge of oxygen than nitrogen.
Lesser atomic size of oxygen than nitrogen
Greater interelectron repulsion between two electrons in the same p-orbital counter balances the increase in effective nuclear charge on moving from nitrogen to oxygen.
Greater effective nuclear charge of oxygen than nitrogen.
Column I | Column II | ||
(A) | He | (i) | High electron affinity |
(B) | Cl | (ii) | Most electropositive element |
(C) | Ca | (iii) | Strongest reducing agent |
(D) | Li | (iv) | Highest ionisation energy |
A-iv, B-i, C-ii, D-iii
A-iii, B-i, C-ii, D-iv
A-iv, B-iii, C-ii, D-i
A-ii, B-iv, C-i, D-iii
Identify the nuclear reaction that differs from the rest.
γ- decay
κ- capture
Positron emission
β-decay
Using the following thermochemical equations
(i) S(rh) + 3/2O2(g) → SO3 (g) ΔH = -2x kJ mol-1
(ii) SO2(g) + 1/2O2 (g) → SO3 (g) ΔH = -y kJ mol-1
Find out the heat of formation of SO2 (g) in kJ mol-1.
(2x + y)
(x + y)
(2x/y)
(y- 2x)
The lattice enthalpy and hydration enthalpy of four compounds are given below
Compound | Lattice enthalpy (in kJ mol-1) | Hydration enthalpy (in kJ mol-1) |
P | +780 | -920 |
Q | +1012 | -812 |
R | +828 | -878 |
S | +632 | -600 |
The pair of compound which is soluble in water is
P and R
Q and R
P and Q
Rand S
1.6 moles of PCl5(g) is placed in 4 dm closed vessel. When the temperature is raised to 500 K, it decomposes and at equilibrium 1.2 moles of PCl5(g) remains. What is the K, value for the decomposition of PCl5(g) to PCl3(g) and Cl5(g) at 500 K?
0.013
0.050
0.033
0.067
C.
0.033
For a concentrated solution of a weak electrolyte AxBy of concentration 'C', the degree of dissociation 'a' is given as
α = √ Keq/ C ( x + y)
α = √ Keq/ C ( xy)
α =( Keq/ Cxy)
α =( Keq/ Cxy)