Periodic Trends — Set 3
Chemistry · आवर्ती प्रवृत्तियां · Questions 21–30 of 50
Which of the following sets of elements represents Dobereiner's Triads?
Correct Answer: D. Li, Na, K
Lithium, Sodium, and Potassium form a Dobereiner's triad. In these triads, the atomic weight of the middle element is roughly the average of the other two. This was an early attempt at classifying elements.
Which element has the electronic configuration [Ar] 4s¹?
Correct Answer: C. Potassium
Potassium has the atomic number 19 and ends its configuration in 4s¹. It is a highly reactive alkali metal found in Group 1. It must be stored in oil to prevent reaction with air.
As we move across a period, the non-metallic character of elements?
Correct Answer: A. Increases
Non-metallic character increases from left to right across a period. This is because elements gain a stronger tendency to attract electrons. Fluorine, at the end of the period, is a prime example of a non-metal.
Which period in the modern periodic table is the shortest?
Correct Answer: C. Period 1
Period 1 is the shortest period as it contains only two elements. These elements are Hydrogen and Helium. It corresponds to the filling of the first electron shell.
Which of the following is not an alkaline earth metal?
Correct Answer: B. Sodium
Sodium is an alkali metal, not an alkaline earth metal. Alkaline earth metals belong to Group 2 of the periodic table. They are generally harder and less reactive than alkali metals.
The shielding effect is most prominent in which type of orbitals?
Correct Answer: C. s-orbitals
The shielding effect is strongest in s-orbitals because they are closest to the nucleus. Inner electrons block the attraction between the nucleus and outer electrons. This effect influences the ionization energy and atomic size.
Transition elements are found in which block of the periodic table?
Correct Answer: A. d-block
Transition elements occupy the d-block between groups 2 and 13. They are characterized by the filling of inner d-orbitals. These metals often form colored compounds and act as catalysts.
Which element has the highest boiling point in the periodic table?
Correct Answer: B. Tungsten
Tungsten has the highest boiling point and melting point of all metallic elements. It is commonly used as a filament in incandescent light bulbs. Its chemical symbol W comes from its German name Wolfram.
The size of an anion is ________ than its parent neutral atom.?
Correct Answer: A. Larger
Anions are larger than their parent atoms because they have extra electrons. The addition of electrons increases electron-electron repulsion. This causes the electron cloud to expand outward.
Modern Periodic Law was discovered by which scientist?
Correct Answer: B. Henry Moseley
Henry Moseley established that atomic number is the fundamental property of an element. This discovery shifted the basis of the periodic table from atomic mass to atomic number. It resolved many inconsistencies found in earlier tables.