This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Position of the Periodic Table”.
1. All d-block elements are transition elements.
Explanation: Scandium and Zinc are d-block elements but are not transition elements. The electronic configurations of Sc and Zn are:
Sc: [Ar] 3d14s2
Zn: [Ar] 3d104s2
In their ionic form, Sc and Zn lose electrons and attain the configuration of Argon. Hence, they have completely filled d orbitals.
2. What is the general electronic configuration of d-block elements?
Explanation: D-block elements are so-called since, in them, 3d, 4d, 5d and 6d subshells are incomplete and the last electron enters the (n-1)d orbital, i.e., penultimate (last but one) shell. Their general electronic configuration is (n-1)d1-10ns0-2, where n is the outermost shell.
3. How many series’ of transition elements are present in the periodic table?
Explanation: Unlike s or p block elements which are usually discussed as columns or groups, d-block elements are better discussed by classifying them into horizontal series. In the periodic table, there are four main transition series of elements corresponding to filling of 3d, 4d, 5d and 6d sublevels in the 4th, 5th, 6th and 7th periods.
4. The study of transition elements is useful.
Explanation: The study of transition elements is important because precious metals such as silver, gold and platinum as well as industrially important metals such as iron, copper and titanium are transition elements.
5. Which of the following element is not a transition element?
Explanation: All transition elements are d-block elements, but all d-block elements are not transition elements. Zinc has the electronic configuration [Ar] 3d104s2, and the configuration of the Zn2+ ion is [Ar] 3d10. Thus, both the element and its only known stable ion have completely filled d-orbitals. Also, the metal does not exhibit any variable valency or multiple oxidation states in compound formation.
6. Which of the following element belongs to the first transition series of the periodic table?
Explanation: The first transition series or 3d series corresponding to the filling of 3d sublevel consists of the following 10 elements of the 4th period: Sc (Atomic No. = 21), Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn (Atomic No. = 30).
7. Which of the following element belongs to the second transition series of the periodic table?
Explanation: The second transition series or 4d series corresponding to the filling of 4d sublevel consists of the following 10 elements of the 5th period: Y (Atomic No. = 39), Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag and Cd (Atomic No. = 48).
8. Which of the following element belongs to the third transition series of the periodic table?
Explanation: The third transition series or 5d series corresponding to the filling of 5d sublevel consists of the following 10 elements of the 6th period: La (Atomic No. = 57); Hf (Atomic No. = 72), Ta, W, Re, Os, Ir, Pt, Au and Hg (Atomic No. = 80).
9. What is the first element of the fourth transition series in the periodic table?
Explanation: The fourth transition series or 6d series corresponding to the filling of 6d sublevel starts with Actinium (Atomic No. = 89) followed by elements with atomic number 104 onwards. These elements lie in the seventh period of the periodic table.
10. What is the nature of the transition elements?
d) Varies from element to element
Explanation: Because they are all metals, the transition elements are often called the transition metals. As a group, they display typical metallic properties and are less reactive than the metals in group 1 and group 2 of the periodic table.
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