Which of the following processes does not involve the oxidation of iron?
1. | Rusting of iron sheets |
2. | Decolourisation of blue CuSO4 solution by iron |
3. | Formation of Fe(CO)5 from Fe |
4. | Liberation of H2 from steam by iron at high temperature |
The pair of compounds that can exist together is:
1. FeCl3, SnCl2
2. HgCl, SnCl2
3. FeCl2, SnCl2
4. FeCl3, Kl
In acidic medium, H2O2 changes Cr2O7–2 to CrO5 which has two (–O – O–) bonds.
The oxidation state of Cr in CrO5 is:
1. +5
2. +3
3. +6
4. -10
The reason for the lanthanoid contraction is:
1. negligible screening effect of 'f' orbitals.
2. increasing nuclear charge.
3. decreasing nuclear charge.
4. decreasing screening effect.
Which of the following statements is false?
1. | On passing H2S through acidified K2Cr2O7 solution, a milky colour is observed. |
2. | Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis. |
3. | K2Cr2O7 solution in an acidic medium is orange. |
4. | K2Cr2O7 solution becomes yellow in increasing the pH beyond 7 |
For the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?
(At. No Cr= 24, Mn= 25, Fe=26, Co= 27)
1. Fe>Mn>Co>Cr
2. Co>Mn>Fe>Cr
3. Cr>Mn>Co>Fe
4. Mn>Fe>Cr>Co
1. | The greater metallic character of the lanthanoids than that of the corresponding actinoids. |
2. | More energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals. |
3. | The lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals. |
4. | More active nature of the actinoids. |