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

Total Questions: 49

41. Which of the given statements is/are true? [RRB ALP Tier - I (30/08/2018) Afternoon]

A. The 2ⁿᵈ group elements are called  Alkali metals.
B. The 1ˢᵗ group elements are called  Alkaline metals.
C. The 17ᵗʰ group elements are called  Halogens.

Correct Answer: (c) Only C
Solution:

The 2nd group elements {Beryllium (Be) to Radium (Ra)} are called Alkaline Earth Metals, have ns² outermost configuration and belong to the s-Block Elements. The 1st group elements {Lithium (Li) to Francium (Fr)} are called Alkali Metals, have ns¹ outermost configuration and belong to the s-block Elements.
The 17th group elements {Fluorine (Fl) to Ununseptium (Uus)/Tennessee (Ts)} are called Halogens and have ns² np⁵ outermost configuration and belong to the p-Block Elements.

42. Which of the following has the largest sized atoms? ( periodic table) [RRB ALP Tier - I (30/08/2018) Evening]

Correct Answer: (b) Al
Solution:

While moving left to right across a period in the periodic table, the atomic number increases. From right to left in the periodic table the atomic radius increases. Aluminium (Al, Atomic Number 13) is group 13 element, Silicon (Si, Atomic Number 14) is group 14 element, Phosphorus (P, Atomic Number 15) is group 15 element, and Sulphur (S, Atomic Number 16) is group 16 element. Therefore Aluminium has the largest sized atoms.

43. Which of the following statements is most appropriate for transition elements? (periodic table) [RRB ALP Tier - I (30/08/2018) Evening]

Correct Answer: (c) Two of their outermost shells are incomplete.
Solution:

Transition element is defined as the one which has incompletely filled “d” orbitals in its ground state or in any one of its oxidation states. All the transition elements display typical metallic properties such as high tensile strength, ductility, malleability, high thermal and electrical conductivity and metallic luster. With the exceptions of zinc (Zn), cadmium (Cd), mercury (Hg) and Manganese (Mn).

44. Which of the following elements was the last element in Newland's Law of Octaves? [RRB ALP Tier - I (31/08/2018) Morning]

Correct Answer: (b) Thorium
Solution:

Newland's law of octave is the first to classify elements arranged according to their increasing atomic weights then every eight elements has similar properties as the first element. His law was applicable up to calcium. After calcium, this law didn't give the proper results. That's the reason this law got discarded.

45. In the Modern Periodic Table elements present in the same period will have the same: [RRB ALP Tier - I (31/08/2018) Afternoon]

Correct Answer: (b) number of shells
Solution:

All the elements are arranged in the increasing order of their atomic number. The horizontal rows are called periods (7). Each period represents a specific energy level that the electrons occupy around the nucleus of an atom. Vertical columns are called groups (18) groups in the periodic table.

46. The element with the highest electron affinity among halogens is: [RRB ALP Tier - I (31/08/2018) Afternoon]

Correct Answer: (c) CI
Solution:

Electron affinity - Cl (chlorine) >F (Fluorine) >Br (Bromine) >I (Iodine). Properties of halogen group - Low melting and boiling points, high electronegativities, and are sparingly soluble in water.
Uses of Halogen gas - Fire extinguishers (Bromine), dental health (Fluorine), refrigerants in air condition and freezer, in producing thyroid hormones (iodine).

47. Given in the options are sets of particular characteristics of elements and how they vary across the period and down the group in the following format: Characteristic of an element- Across the period - Down the group Select the correct set from the given options. [RRB ALP Tier - I (31/08/2018) Evening]

Correct Answer: (c) Electropositive character/metallic character- Decrease - Increase
Solution:

The modern periodic table consists of vertical columns called groups and horizontal rows called periods. The elements are arranged based on the increasing atomic numbers.
Atomic radius decreases as we move from left to right across a period in the periodic table and increases as we move from top to bottom down a group. Ionic radius decreases as we move from left to right across a period in the periodic table and increases as we move from top to bottom down a group. Ionization energy increases on going from left to right across a period and decreases on moving down a group.

48. An element with electronic configuration of 2, 8, 6 is placed in the group _____ in the modern periodic table. [RRB Group D 25/10/2018 (Afternoon)]

Correct Answer: (a) 16
Solution:

Since, the electronic configuration of the given element is 2, 8, 6. Therefore, its atomic number will be 2 + 8 + 6 = 16. This implies that the given element is Sulphur.

49. Three elements A, B and C form Dobreiner's triad. If the atomic mass of element A is 7 and the atomic mass of element C is 39, then what will be the atomic mass of element B ? [RRB Group D 14/12/2018 (Afternoon)]

Correct Answer: (b) 23
Solution:

According to Döbereiner’s triads, the atomic mass of the middle element is approximately the arithmetic mean of the atomic masses of the first and third elements.