The oxidation number is changed in which of the following case

1. SO₂ gas is passed into $C{r}_2{O}_7^{2-}/H^{+}$

2. Aqueous solution of $Cr{O}_4^{2-}$ is acidified

3. $Cr{O}_{2}C{l}_2$ is dissolved in NaOH

4. $C{r}_2{O}_7^{2-}$ solution is made alkaline

Which of the following elements form stable dinuclear ions

1. Zn

2. Cd

3. Hg

4. Fe

The correct electronic configuration of Ti(Z=22 atom) is

(1) $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^2$

(2) $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{2}4p^6$

(3) $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^4$

(4) $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^2$

The correct statement regarding colour of Zn²⁺, Ni²⁺and Cr³⁺among the following is:

The incorrect statement regarding the transition metals is:

Assertion: Transition metals have high boiling points and high enthalpy of atomization.

Reason: The transition metals occur in bcc, hcp or ccp structures charcterstics of metals.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion
3. Assertion is true but reason is false
4. Both assertion and reason are false

Assertion: Zn, Cd and Hg are normally not considered transition metals.

Reason: d-orbitals in above elements are completely filled, hence above metals do not show the general charcterstic properties of the transition elements.

Assertion :A transition metal forms alloy with other transition metal easily.

Reason: The transition metals have similar electronic configuration,nearly equal radii and exhibit similar packing in their lattices.

Assertion : Anhydrous copper(II) chloride is a covalent while anhydrous copper(II)fluoride is ionic in nature.

Reason: In halides of transition metals, the ionic character decreases with increase in atomic mass of the halogen.

Assertion: E^o for Mn³⁺/Mn²⁺ couple is more positive than for Fe³⁺/Fe²⁺.

Reason: Mn³⁺ has d⁴ configuration and Fe³⁺ has a d⁵ configuration.