Classification of elements and Periodicity in properties MCQs for NEET — Chemistry Questions with Answers

Mercury (1) is a liquid metal (s), Carbon in the form of Diamond (2) has an extremely high melting point (t), Bromine (3) is a liquid non-metal (p), and Caesium & Fluorine (4) react very violently (q). Therefore, the correct match is 1–s, 2–t, 3–p, 4–q.

Inner transition elements belong to the f-block (s), transition elements are part of the d-block (r), typical elements are found in the 3rd period (p), and representative elements belong to the s & p blocks (q).

Beryllium and Aluminum show a diagonal relationship (r), the Aufbau principle represents the rule for filling electrons in orbitals (s), elements with general electronic configuration $ns^2 np^{1– 5}$ belong to the p-block (q), and elements with electronic configuration $ns^2 np^6$ are noble gases (p).

For atomic number Z = 34, the element is Selenium (Se), which belongs to the Chalcogen group. For atomic number Z = 37, the element is Rubidium (Rb), which is a representative element. Hence, the correct answer is 'Chalcogen & representative.'

The size of an ion is influenced by its nuclear charge and the number of electrons. The correct order of decreasing atomic size is $ S ^ {2-} ightarrow Cl ^ {-} ightarrow Ar ightarrow K ^ {+} ightarrow Ca ^ {2+} $ because as the nuclear charge increases and the number of electrons decreases, the atomic size decreases.

The reaction $ O ightarrow O ^ {2-} $ requires maximum energy because adding two electrons to oxygen to form $ O ^ {2-} $ involves overcoming a significant amount of electron-electron repulsion within the same orbital, making this process require more energy compared to the others.

The electronegativity of elements generally increases across a period and decreases down a group. Therefore, the order of increasing electronegativity is Si (Silicon), P (Phosphorus), C (Carbon), N (Nitrogen).