Oxidation States of Lanthanides

Q. In chromite ore, the oxidation number of iron and chromium are respectively

1. +3, +2
2. +3, +2
3. +2, +6
4. +2, +3.

Q.

The highest oxidation state exhibited by Xenon is:

1. +2

2. +4

3. +6

4. +8

Q. In aqueous solution, Eu${}^2+$ ion acts as a/an

1. oxidizing agent
2. reducing agent
3. either a) or b)
4. none of these.

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> For the second period elements the correct increasing order of first ionisation enthalpy is:

NEET 2019

1. $Li<Be<B<C<O<N<F<Ne$
2. $Li<B<Be<C<N<O<F<Ne$
3. $Li<Be<B<C<N<O<F<Ne$
4. $Li<B<Be<C<O<N<F<Ne$

Q. The reason for the stability of $G{d}^{+3}$ ion is:

1. A half filled 4f subshell
2. A completely filled 4f subshell
3. It possesses the general electronic configuration of a noble gas
4. It has an empty 4f subshell

Q. In aqueous solution, Eu${}^2+$ ion acts as a/an

1. oxidizing agent
2. reducing agent
3. either a) or b)
4. none of these.

Q. Which one of the followng statements related to lanthanides is incorrect ?

1. All the lanthanoids are much more reactive than aluminium
2. Ce(+4) solutions are widely used as oxidizing agent in volumetric analysis
   
3. Europium shows +2 oxidation state
4. The basicity decreases as the ionic radius decreases from Pr to Lu.

Q. Choose incorrect option for 3-d transition series:-

1. Density increases from Ti to Cu
2. first ionization enthalpy is highest for zinc
3. enthalpy of atomization is lowest for manganese
4. Cr${}^{2+}$ is a strong reducing agent

Q. The reason for the stability of Gd${}^3+$ ion is

1. 4 f sub shell empty
2. 4 f sub shell- completely filled
3. Possesses the general electronic configuration of noble gases
4. 4 f sub shell- half filled