At pH = X, \(\text{CrO}_4^{2-}\) (yellow) changes to \(\text{Cr}_2\text{O}_7^{2-}\) (orange), and vice versa at pH = Y.
What are the values of X and Y, respectively?
1. 6, and 8
2. 6, and 5
3. 8, and 6
4. 7, and 7
Which of the following solid salt on heating with K2Cr2O7 and Conc. H2SO4 orange,red vapours are evolved which turn aquous NaOH solution yellow?
1. NaBr
2. NaCl
3. NaNO3
4. NaI
With F highest stable oxidation state of Mn is
1. +6
2. +4
3. +7
4. +3
The correct electronic configuration of Gadolinium(Atomic number = 64) is :
1. [Xe]4f86d2
2. [Xe]4f95s1
3. [Xe]4f75d16s2
4. [Xe]4f65d26s2
KMnO4 can be prepared from K2MnO4 as per reaction
The reaction can go to completion by removing OH- ions by adding
1. HCl
2. KOH
3. CO2
4. SO2
Which of the following species is colourless?
1. and
2. Cu2Cl2 and
3. and Cu2Cl2
4. and
A mixture of Mn2+ & Zn2+ can be separated by using an excess of
(1) NH4OH
(2) NaOH
(3) H2SO4
(4) HNO3
The hardest lanthanide is
1. La
2. Lu
3. Sm
4. Yb
A substance is found to have a magnetic moment of 3.9 B.M. The ion may be
1. Fe+3
2. Mn+2
3. Co+2
4. Cu+2
The number of moles of Mohr's salt required per mole of dichromate ion is:
(1) 3
(2) 4
(3) 5
(4) 6
Which of the following is a result of the lanthanide contraction?
1. Zr and Y have nearly the same atomic radius.
2. Zr and Zn have the same oxidation state.
3. Zr and Hf have nearly the same atomic radius.
4. Zr and Nb have similar oxidation states.
Actinoids show a greater number of oxidation states than lanthanoids because:
1. | 4f- orbitals are more diffused than 5f-orbitals |
2. | Lesser energy difference between 5f, and 6d orbitals than between 4f, and 5d orbitals |
3. | More energy difference between 5f, and 6d orbitals than between 4f, and 5d orbitals |
4. | More reactive nature of the actinoids than the lanthanoids. |