Variable Oxidation States

Q.

Why cu2+ more stabler than cu+ though cu+ has completely filled d orbital?

Q. Which of the following has the maximum number of unpaired electrons?
( Given Atomic number: $Sc=21,Fe=26,V=23,Ni=28)$

1. $V^{4+}$
2. $N{i}^{2+}$
3. $S{c}^{2+}$
4. $F{e}^{3+}$

Q. What is the oxidation number of $Cl$ in $CaOC{l}_2$?

1. 1
2. -1
3. \N
4. -2

Q. Calculate the ‘spin only’ magnetic moment of $M^{2+}\left(aq\right)$ ion $(Z=27)$.

Q.

What are the oxidation states of copper?

Q. Is boron a metal or non metal?

Q. The highest oxidation state of manganese in fluorides is 4+ (MnF₄) but the highest oxidation state in oxides is 7+ (Mn₂O₇) because:

1. In covalent compounds fluorine can form single bond while oxygen forms double bond
2. Fluorine stabilises lower oxidation state
3. Fluorine does not possess d-orbitals
4. Fluorine is more electronegative than oxygen

Q.

The calculated magnetic moments (spin only value) for species ${\left[{\mathrm{FeCl}}_4\right]}^{2-}$, ${\left[\mathrm{Co}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]}^{3-}$and ${{\mathrm{MnO}}_4}^{2-}$respectively are:

1. $5.92\mathrm{BM},4.90\mathrm{BM}\mathrm{and}0\mathrm{BM}$

2. $5.82\mathrm{BM},0\mathrm{BM}\mathrm{and}0\mathrm{BM}$

3. $4.90\mathrm{BM},0\mathrm{BM}\mathrm{and}1.73\mathrm{BM}$

4. $4.90\mathrm{BM},0\mathrm{BM}\mathrm{and}2.83\mathrm{BM}$

Q.

Why do d-block elements form complexes?

Q.

Oxidation number of C in CO₂ is_____

Q. Which is the most common oxidation state of lanthanides and actinide series?

1. +3 and +4
2. +2 and +3
3. +3 only
4. +2 only

Q.

Which transition element does not exhibit variable oxidation states?

Q. The highest oxidation state of manganese in fluorides is 4+ (MnF₄) but the highest oxidation state in oxides is 7+ (Mn₂O₇) because:

1. In covalent compounds fluorine can form single bond while oxygen forms double bond
2. Fluorine stabilises lower oxidation state
3. Fluorine does not possess d-orbitals
4. Fluorine is more electronegative than oxygen

Q. Name the three lanthanides which show +2 oxidation state also : (1) Sm, Tb, Gd (2) Sm, Eu, Yb (3) La, Gd, Lu (4) Yb, Pm, Sm

Q. Which among the following is the most stable?

1. $T{i}^{2+}$
2. $T{i}^{3+}$
3. $T{i}^{4+}$
4. All are equally stable

Q. How the acidified permanganate solution reacts with oxalic acid?

1. $2Mn{O}_4^{-}+16H^{+}+5C_2{O}_4^{2-}\to 2M{n}^{2+}+8H_{2}O+10C{O}_2$
2. $3Mn{O}_4^{-}+16H^{+}+7C_2{O}_4^{2-}\to 3M{n}^{2+}+8H_{2}O+14C{O}_2$
3. $3Mn{O}_4^{-}+14H^{+}+5C_2{O}_4^{2-}\to 3M{n}^{2+}+7H_{2}O+10C{O}_2$
4. None of these

Q.

Account for:

$\mathrm{MnO}$ is basic whereas ${\mathrm{Mn}}_2{\mathrm{O}}_7$is acidic in nature why?

Q.

The decreasing order of relative stability of $+1$ oxidation state of group $13$ elements is

1. $\mathrm{Al}<\mathrm{Ga}<\mathrm{In}<\mathrm{Tl}$

2. $\mathrm{Al}<\mathrm{Ga}<\mathrm{Tl}<\mathrm{In}$

3. $\mathrm{Ga}<\mathrm{Al}<\mathrm{In}<\mathrm{Tl}$

4. $\mathrm{Tl}<\mathrm{In}<\mathrm{Ga}<\mathrm{Al}$

Q.

What is the average oxidation state of $\mathrm{S}$ atoms in ${\mathrm{H}}_2{\mathrm{S}}_4{\mathrm{O}}_6$?

Q.

Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?

Q.

How is the variability in oxidation states of transition metals different from that of non-transition metals? Illustrate with examples.

Q. In MnO4- , there is no electron in d orbital but it is coloured ion. Explain.

Q.

The third ionisation enthalpy is the lowest for:

1. $\mathrm{Mn}$

2. $\mathrm{Co}$

3. $\mathrm{Ni}$

4. $\mathrm{Fe}$

Q.

Name the most abundant metal in the Earth’s crust. Also name its most important ore.

Q. What is the oxidation state of mercury in Nessler's reagent?

1. 4
2. 1
3. 2
4. 0

Q. Alkali metals are paramagnetic not their metals

Q. Which is not amphoteric

1. $A{l}^{3+}$
2. $C{r}^{3+}$
3. $Z{n}^{2+}$
4. $F{e}^{3+}$

Q. Which of the following is correct when the following equilibrium is established when C and water is placed in a container?
$C\left(s\right)+H_{2}O\left(g\right)\rightleftharpoons CO\left(g\right)+H_2\left(g\right)$

1. $P_{H_2}\propto P_{H_{2}O}$
2. $P_{H_2}\propto \sqrt{P_{H_{2}O}}$
3. $P_{H_2}\propto P_{H_{2}O}^2$
4. $P_{H_2}\propto \frac{P_{H_{2}O}^2}{P_{CO}}$

Q.

An element having configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$ will form_.

Q.

Why the stability of $+6$ the oxidation state in a group $16$ decreases down the group and $+4$ increases down the group?