Railway Science (Chemistry-Periodic Table) (Part-VI)

Total Questions: 50

21. Mendeleev could not assign a correct position to which of the following elements in his table ? [RRB Group D 25/10/2018 (Morning)]

Correct Answer: (c) Hydrogen
Solution:

It exhibits properties similar to both alkali metals (loses one electron to form a positive ion) and halogens (gains one electron to form a negative ion).

22. Which element in the periodic table forms the maximum number of compounds ? [RRB Group D 25/10/2018 (Morning)]

Correct Answer: (d) C
Solution:

C (Carbon), with its unique combination of properties like tetravalency, catenation (forming long chains), and ability to form multiple bonds, can form an incredible number of organic and inorganic compounds.
This versatility contributes to its title as the "king of elements" in terms of compound formation.

23. Arrange the following elements in the order of their increasing non-metallic properties: Li, O, C, Be, F. [RRB Group D 26/10/2018 (Afternoon)]

Correct Answer: (b) Li < Be < C < O < F
Solution:

Non-metals are located at the top right hand side of the Periodic Table. In fact, in a horizontal row, the property of elements changes from metallic on the left to non-metallic on the right.
Non-metals are usually solids or gases at room temperature with low melting and boiling points (boron and carbon are exceptions).
They are poor conductors of heat and electricity. Non-metallic character increases as one goes from left to right across the Periodic Table.

24. Which of the following statements is/are true? [RRB Group D 26/10/2018 (Evening)]

A. Of the 114 elements, 22 are nonmetals, and the others are ores.
B. Every ore is a mineral but not every mineral is an ore.

Correct Answer: (d) Only B is true
Solution:

In the Modern Periodic Table, a zig-zag line separates metals from non-metals. Some of the examples of non-metals are carbon, sulphur, iodine, oxygen, hydrogen, etc.
The non-metals are either solids or gases except bromine which is a liquid. The non-metals are bad conductors of heat and electricity, except for graphite, which conducts electricity.

25. Which of the following points are correct regarding electronic configuration [RRB Group D 26/10/2018 (Evening)]

a. This is the arrangement of electrons in the shells of an atom.
b. This is the arrangement of electrons in subshells.
c. It is the arrangement of electrons in the orbitals of an atom.

Correct Answer: (a) a, b, c all three
Solution:

The distribution of electrons into orbitals of an atom is called its electronic configuration. Orbitals are grouped into subshells, which are further grouped into shells. The shells are numbered by the principal quantum number (n), and the subshells are denoted by the azimuthal quantum number (l).

26. The maximum valency of the halogen group with respect to oxygen is ________. [RRB Group D 26/10/2018 (Evening)]

Correct Answer: (b) 7
Solution:

The halogens are highly reactive non-metallic elements. Fluorine, chlorine, bromine, iodine and astatine are members of Group 17. These are collectively known as the halogens. The halogens have the smallest atomic radii in their respective period due to maximum effective nuclear charge.

27. In Mendeleev's periodic table, in what order were the elements arranged? [RRB Group D 26/10/2018 (Evening)]

Correct Answer: (a) In increasing order of atomic masses
Solution:

Mendeleev arranged the elements in the increasing order of their atomic masses in horizontal rows till he came across an element whose properties were similar to those of the first element.
Mendeleev’s Periodic Law - The chemical and physical properties of elements are a periodic function of their atomic masses.

28. ______ is a purple-coloured solid halogen. [RRB Group D 29/10/2018 (Morning)]

Correct Answer: (d) Iodine
Solution:

Atomic number (z) = 53. The Group 17 elements are known as the Halogen (non-metals). The word halogen means 'salt forming' compounds. Since all halogens have 7 electrons in their valence shell, they react rapidly with metals to form salts.
Example - Fluorine, Chlorine, Bromine, and Iodine, Astatine (At), Tennessine (Ts). Fluorine (F, z = 9) - Pale yellow, Chlorine (Cl, z = 17) - Greenish Yellow, Bromine (Br, z = 35) - Red brown.

29. The elements belonging to groups ________ are known as 'd' block elements. [RRB Group D 29/10/2018 (Morning)]

Correct Answer: (a) 3 to 12
Solution:

'd' block elements also referred to as transition elements or transition metals. 'd' block elements example : Scandium (Sc, 21), Titanium (Ti, 22), Vanadium (V, 23), Chromium (Cr, 24), Manganese (Mn, 25), Iron (Fe, 26), Cobalt (Co, 27), Nickel (Ni, 28), Copper (Cu, 29) and Zinc (Zn, 30). s-block - elements of Groups 1 and 2. p-block - elements of Groups 13 to 18.

30. How does the Metallic Character of an element vary in the Modern Periodic Table ? [RRB Group D 29/10/2018 (Evening)]

Correct Answer: (b) The Metallic Character decreases from left to right in a period but increases from top to bottom in a group
Solution:

Metallic character- Depends on the ability of the element to lose the valence electron. Dmitri Mendeleev (Russian chemist) developed the periodic classification of the elements in 1869.