Short Answer TypeCopper crystallises with face centred cubic unit cell. If the radius of a copper atom is 127.8 pm, calculate the density of the copper metal.
(Atomic mass of Cu = 63.55 u and Avogadro’s number NA = 6.02 x 1023 mol-1)
Iron has a body centred cubic unit cell with the cell dimension of 286.65 pm. The density of iron is 7.87 g cm-3. Use this information to calculate Avogadro’s number. (Atomic mass of Fe = 56.0 u)
The reaction N2(g) + O2(g) 2NO(g), contributes to air pollution whenever a fuel is burnt in air at a high temperature. At 1500 K, equilibrium constant K for it is 1.0 x 10-5. Suppose in a case [N2] = 0.80 mol L-1and [O2] = 0.20 mol L-1 before any reaction occurs. Calculate the equilibrium concentrations of the reactants and the product after the mixture has been heated to 1500 K.
The electrical resistance of a column of 0.05 M NaOH solution of diameter 1cm and length 50
cm is 5.55 x 103 ohm. Calculate its resistivity, conductivity and molar conductivity.
Write three distinct features of chemisorptions which are not found in physisorptions.
Chemisorption is a kind of adsorption which involves a chemical reaction between the surface and the adsorbate.
Physisorption, also called physical adsorption, is a process in which the electronic structure of the atom or molecule is barely perturbed upon adsorption.
|
S. No. |
Point of difference |
Physiosorption |
Chemisorption |
|
(i) |
Specificity |
This is not specific in nature. |
This is highly specific in nature. |
|
(ii) |
Temperature dependence |
Low temperature is favourable for physiosorption. It decreases with increase in temperature. |
High temperature is favourable for chemisorption. It increases with the increase in temperature. |
|
(iii) |
Reversibility |
This is reversible in nature. |
This is irreversible in nature. |
|
(iv) |
Enthalpy change |
Enthalpy of adsorption is low. |
Enthalpy of adsorption is high. |
Explain each of the following observations:
(i) With the same d-orbital configuration (d4), Cr2+ is a reducing agent while Mn3+ is an oxidising agent.
(ii) Actinoids exhibit a much larger number of oxidation states than the lanthanoids.
(iii) There is hardly any increase in atomic size with increasing atomic number in a series of transition metals.
Name of the following coordination entities and describe their structure:
(i) [Fe (CN)6]4-
(ii) [Cr (NH3)4Cl2]+
(iii) [Ni (CN) 4]2-
(Atomic numbers Fe = 26. Cr = 24, Ni = 28Write a reaction which shows that all the carbon atoms in glucose are linked in a straight chain.
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