d and f BLOCK ELEMENTS MCQ Quiz: GKFix - Bridge of Knowledge - Page 348

Question 1736

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What is the primary reason for the lanthanoid contraction?

Increase in nuclear charge
Imperfect shielding of 4f electrons
Increase in atomic mass
Perfect shielding of 4f electrons

Question 1737

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What is the role of the 4f orbitals in determining the properties of 5d series elements?

They provide excellent shielding for 5d electrons
Their poor shielding causes Lanthanoid contraction, affecting 5d element sizes
They determine the number of valence electrons in 5d elements
They have no effect on 5d element properties

Question 1738

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Why is the term 'noble character in reactions' used for metals with high enthalpies of atomisation?

Because they are gases
Because they are highly coloured
Because the high energy barrier for atomisation makes them less reactive
Because they have low density

Question 1739

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How does the concept of effective nuclear charge help explain the trends in transition metal radii?

It decreases across a series due to effective d shielding
It remains constant across a series
It increases across a series due to poor d shielding, pulling electrons closer
It fluctuates randomly across a series

Question 1740

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What is the consequence of the poor shielding effect of f electrons across the lanthanide series?

Regular increase in atomic radii
No change in atomic radii
Regular decrease in atomic radii (Lanthanoid contraction)
Random fluctuation in atomic radii