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

The lanthanide compound which is used as a most powerful liquid laser after dissolving in selenium oxychoride is 

1. Cerium oxide

2. Neodymium oxide

3. Promethium sulphate

4. Cerium sulphate

Which of the following weighs lesser when weighed in the magnetic field? 

1. ScCl₃

2. FeCl₃

3. TiCl₃

4. VCl₃

Reason for lanthanoid contraction is:

1. Negligible screening effect of 'f' orbitals

2. Increasing nuclear charge

3. Decreasing nuclear charge

4. Decreasing screening effect

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

Basic oxide is

1. CrO

2. ${\mathrm{Cr}}_2{\mathrm{O}}_3$

3. ${\mathrm{CrO}}_3$

4. ${\mathrm{Cr}}_2{\mathrm{O}}_4$

In dichromate dianion

Lanthanoid which is radioactive is