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CHXII08:THE D- & F-BLOCK ELEMENTS

321237 Coloured and paramagnetic oxoanion is:

1

{MnO}_{4}^{-}

2

{CrO}_{4}^{- 2}

3

{MnO}_{4}^{- 2}

4

{Cr}_{2} O_{7}^{- 2}

Explanation:

${MnO}_{4}^{- 2}$ is green coloured due to $L \to M$ charge transfer. Oxidation state of ${Mn}^{+ 6}$ .
$M n^{+ 6} = [A r] 4 s^{0} 3 d^{1} (1 unpaired e^{-})$

CHXII08:THE D- & F-BLOCK ELEMENTS

321238 ${CrO}_{3}$ dissolves in aqueous $NaOH$ to give

1

{CrO}_{4}^{2 -}

2

Cr (OH)_{3}

3

{Cr}_{2} O_{7}^{2 -}

4

Cr (OH)

Explanation:

${CrO}_{3} + 2 NaOH \to \underset{Yellow solution}{{Na}_{2} {CrO}_{4}} + H_{2} O$

CHXII08:THE D- & F-BLOCK ELEMENTS

321239 Which oxide of first transition series is not amphoteric in nature?

1

V_{2} O_{5}

2 ZnO

3

{Cr}_{2} O_{3}

4

{Sc}_{2} O_{3}

Explanation:

Scandium oxide $({Sc}_{2} O_{3})$ is a basic oxide. $V_{2} O_{5}, {Cr}_{2} O_{3}, ZnO$ are amphoteric in nature.

CHXII08:THE D- & F-BLOCK ELEMENTS

321240 An element $M$ has the electronic configuration $[A r] 3 d^{5} 4 s^{2} .$ Which one of its oxide is unlikely to exist?

1

{MO}_{2}

2

M_{2} O_{3}

3

{MO}_{4}

4

M_{2} O_{7}

Explanation:

Given element 'M' is 'Mn' .
The oxides given by Mn are $M n_{2} O_{7}, M n O_{2}, M n_{2} O_{3}, M n O$ but not $M n O_{4} .$

CHXII08:THE D- & F-BLOCK ELEMENTS

321237 Coloured and paramagnetic oxoanion is:

1

{MnO}_{4}^{-}

2

{CrO}_{4}^{- 2}

3

{MnO}_{4}^{- 2}

4

{Cr}_{2} O_{7}^{- 2}

Explanation:

${MnO}_{4}^{- 2}$ is green coloured due to $L \to M$ charge transfer. Oxidation state of ${Mn}^{+ 6}$ .
$M n^{+ 6} = [A r] 4 s^{0} 3 d^{1} (1 unpaired e^{-})$

CHXII08:THE D- & F-BLOCK ELEMENTS

321238 ${CrO}_{3}$ dissolves in aqueous $NaOH$ to give

1

{CrO}_{4}^{2 -}

2

Cr (OH)_{3}

3

{Cr}_{2} O_{7}^{2 -}

4

Cr (OH)

Explanation:

${CrO}_{3} + 2 NaOH \to \underset{Yellow solution}{{Na}_{2} {CrO}_{4}} + H_{2} O$

CHXII08:THE D- & F-BLOCK ELEMENTS

321239 Which oxide of first transition series is not amphoteric in nature?

1

V_{2} O_{5}

2 ZnO

3

{Cr}_{2} O_{3}

4

{Sc}_{2} O_{3}

Explanation:

Scandium oxide $({Sc}_{2} O_{3})$ is a basic oxide. $V_{2} O_{5}, {Cr}_{2} O_{3}, ZnO$ are amphoteric in nature.

CHXII08:THE D- & F-BLOCK ELEMENTS

321240 An element $M$ has the electronic configuration $[A r] 3 d^{5} 4 s^{2} .$ Which one of its oxide is unlikely to exist?

1

{MO}_{2}

2

M_{2} O_{3}

3

{MO}_{4}

4

M_{2} O_{7}

Explanation:

Given element 'M' is 'Mn' .
The oxides given by Mn are $M n_{2} O_{7}, M n O_{2}, M n_{2} O_{3}, M n O$ but not $M n O_{4} .$

CHXII08:THE D- & F-BLOCK ELEMENTS

321237 Coloured and paramagnetic oxoanion is:

1

{MnO}_{4}^{-}

2

{CrO}_{4}^{- 2}

3

{MnO}_{4}^{- 2}

4

{Cr}_{2} O_{7}^{- 2}

Explanation:

${MnO}_{4}^{- 2}$ is green coloured due to $L \to M$ charge transfer. Oxidation state of ${Mn}^{+ 6}$ .
$M n^{+ 6} = [A r] 4 s^{0} 3 d^{1} (1 unpaired e^{-})$

CHXII08:THE D- & F-BLOCK ELEMENTS

321238 ${CrO}_{3}$ dissolves in aqueous $NaOH$ to give

1

{CrO}_{4}^{2 -}

2

Cr (OH)_{3}

3

{Cr}_{2} O_{7}^{2 -}

4

Cr (OH)

Explanation:

${CrO}_{3} + 2 NaOH \to \underset{Yellow solution}{{Na}_{2} {CrO}_{4}} + H_{2} O$

CHXII08:THE D- & F-BLOCK ELEMENTS

321239 Which oxide of first transition series is not amphoteric in nature?

1

V_{2} O_{5}

2 ZnO

3

{Cr}_{2} O_{3}

4

{Sc}_{2} O_{3}

Explanation:

Scandium oxide $({Sc}_{2} O_{3})$ is a basic oxide. $V_{2} O_{5}, {Cr}_{2} O_{3}, ZnO$ are amphoteric in nature.

CHXII08:THE D- & F-BLOCK ELEMENTS

321240 An element $M$ has the electronic configuration $[A r] 3 d^{5} 4 s^{2} .$ Which one of its oxide is unlikely to exist?

1

{MO}_{2}

2

M_{2} O_{3}

3

{MO}_{4}

4

M_{2} O_{7}

Explanation:

Given element 'M' is 'Mn' .
The oxides given by Mn are $M n_{2} O_{7}, M n O_{2}, M n_{2} O_{3}, M n O$ but not $M n O_{4} .$

CHXII08:THE D- & F-BLOCK ELEMENTS

321237 Coloured and paramagnetic oxoanion is:

1

{MnO}_{4}^{-}

2

{CrO}_{4}^{- 2}

3

{MnO}_{4}^{- 2}

4

{Cr}_{2} O_{7}^{- 2}

Explanation:

${MnO}_{4}^{- 2}$ is green coloured due to $L \to M$ charge transfer. Oxidation state of ${Mn}^{+ 6}$ .
$M n^{+ 6} = [A r] 4 s^{0} 3 d^{1} (1 unpaired e^{-})$

CHXII08:THE D- & F-BLOCK ELEMENTS

321238 ${CrO}_{3}$ dissolves in aqueous $NaOH$ to give

1

{CrO}_{4}^{2 -}

2

Cr (OH)_{3}

3

{Cr}_{2} O_{7}^{2 -}

4

Cr (OH)

Explanation:

${CrO}_{3} + 2 NaOH \to \underset{Yellow solution}{{Na}_{2} {CrO}_{4}} + H_{2} O$

CHXII08:THE D- & F-BLOCK ELEMENTS

321239 Which oxide of first transition series is not amphoteric in nature?

1

V_{2} O_{5}

2 ZnO

3

{Cr}_{2} O_{3}

4

{Sc}_{2} O_{3}

Explanation:

Scandium oxide $({Sc}_{2} O_{3})$ is a basic oxide. $V_{2} O_{5}, {Cr}_{2} O_{3}, ZnO$ are amphoteric in nature.

CHXII08:THE D- & F-BLOCK ELEMENTS

321240 An element $M$ has the electronic configuration $[A r] 3 d^{5} 4 s^{2} .$ Which one of its oxide is unlikely to exist?

1

{MO}_{2}

2

M_{2} O_{3}

3

{MO}_{4}

4

M_{2} O_{7}

Explanation:

Given element 'M' is 'Mn' .
The oxides given by Mn are $M n_{2} O_{7}, M n O_{2}, M n_{2} O_{3}, M n O$ but not $M n O_{4} .$

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