With F highest stable oxidation state of Mn is-

1. + 6

2. + 4

3. + 7

4. + 3

${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-} + \mathrm{X} \stackrel{{\mathrm{H}}^{+}}{\to } {\mathrm{Cr}}^{3+} + {\mathrm{H}}_2\mathrm{O} +$ oxidised product of X
X in the above reaction can not be:
 

1. ${\mathrm{C}}_2{\mathrm{O}}_4^{2-}$

2. ${\mathrm{Fe}}^{2+}$

3. ${\mathrm{SO}}_4^{2-}$

4. ${\mathrm{S}}^{2-}$

Lanthanoid which is radioactive is

In dichromate dianion

Basic oxide is

1. CrO

2. ${\mathrm{Cr}}_2{\mathrm{O}}_3$

3. ${\mathrm{CrO}}_3$

4. ${\mathrm{Cr}}_2{\mathrm{O}}_4$

The pair having similar magnetic moment is

1. ${\mathrm{Ti}}^{3+}, {\mathrm{V}}^{3+}$

2. ${\mathrm{Cr}}^{3+}, {\mathrm{Mn}}^{2+}$

3. ${\mathrm{Mn}}^{2+}, {\mathrm{Fe}}^{3+}$

4. ${\mathrm{Fe}}^{2+}, {\mathrm{Mn}}^{2+}$

Reason for 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 statement is not true?

1. On passing $H_{2}S$ through acidified $K_{2}C{r}_2{O}_7$solution, a milky colour is observed

2. $N{a}_{2}C{r}_2{O}_7$ is preffered over $K_{2}C{r}_2{O}_7$ in volumetric analysis

3. $K_{2}C{r}_2{O}_7$ solution in acidic medium is orange

4. $K_{2}C{r}_2{O}_7$ solution becomes yellow in increasing the pH beyond 7

The fusion of chromite ore (FeCr₂O₄) with Na₂CO₃ in air gives a yellow solution upon the addition of water. Subsequent treatment with H₂SO₄ produces an orange solution.
The yellow and orange colours, respectively, are due to the formation of:

1. Na₂CrO₄ and Na₂Cr₂O₇

2. Cr(OH)₃ and Na₂Cr₂O₇

3. Cr₂(CO₃)₃ and Fe₂(SO₄)₃

4. Cr(OH)₃ and Na₂CrO₄