Question

a) Transition elements are ‘d’ block elements. 

i) Write any four characteristic properties of transition elements.

ii) Cr²⁺ and Mn³⁺ have d⁴ configuration. But Cr²⁺ is reducing and Mn³⁺ is oxidising. Why?

b) Which of the following is not a lanthanoid element?

i) Cerium

ii) Europium

iii) Lutetium

iv) Thorium

Answer 1

a) i) Transition elements are metals, have high melting points and high enthalpy of atomisation, exhibit variable oxidation states, show paramagnetism, form coloured compounds, form complex compounds, show catalytic properties, form interstitial compounds, form alloys etc. (any four properties)

ii) For Cr²⁺ to Cr³⁺ configuration changes from d⁴ to d³ For Mn³⁺ to Mn²⁺ d⁵ configuration results in extra stability due to half-filled configuration,

b) iv) Thorium