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

Total Questions: 50

11. In the Modern Periodic Table, Tellurium (atomic number 52) is surrounded by elements with atomic numbers: [RRC Group D 15/09/2022 (Evening)]

Correct Answer: (b) 34, 51, 53, 84
Solution:

Tellurium (Te): Atomic number - 52. It is a metalloid. Electron configuration - [Kr]  5s² 4d¹⁰ 5p⁴ . Selenium “Se” (34), Antimony “Sb” (51), Iodine “I” (53), Polonium “Po” (84).

12. In which year was Mendeleev's Periodic Table published in a German journal? [RRC Group D 16/09/2022 (Morning)]

Correct Answer: (d) 1872
Solution:

It states that the physical and chemical properties of elements are a periodic function of their atomic weights. Dmitri Mendeleev organized elements into groups and rows according to their physical and chemical behavior. Father of the Modern Periodic Table is Dmitri Mendeleev.

13. In the early days, classification of elements was attempted according to their: [RRC Group D 16/09/2022 (Afternoon)]

Correct Answer: (a) properties
Solution:

Every eighth element has similar properties similar to that of the first element when the elements are arranged in the increasing order of their atomic masses. It was applicable only upto calcium. Mendeleev’s Periodic Table - The properties of elements are the periodic function of their atomic masses.

14. Which element does NOT belong to group number 11 in the Modern Periodic Table? [RRC Group D 16/09/2022 (Afternoon)]

Correct Answer: (d) Hg
Solution:

(Mercury) - It belongs to group 12. Group - A vertical column of the periodic table, based on the arrangement of the outer shell electrons. Group 11 (Transition metals) - Copper (Cu), Silver (Ag), Gold (Au) and Roentgenium (Rg). Properties - Going down the group electronegativity decreases, atomic size increases, metallic Character increases and valence electrons remain the same.

15. Arrange the following element of group 1 in the decreasing order of their atomic radii. Atomic numbers are given in parentheses. [RRC Group D 16/09/2022 (Evening)]

Li (3), K (19), Cs (55), Na (11), Rb (37)

Correct Answer: (c) Cs > Rb>K>Na > Li
Solution:

Alkali metals group is the very first group on the periodic table. Elements and atomic numbers of this group: Lithium (Li, 3), Sodium (Na, 11), Potassium (K, 19), Rubidium (Rb, 37), Cesium (Cs, 55) and Francium (Fr, 87). Hydrogen (H, 1) is exceptionally put in the first group even though it is gas.

16. In the modern periodic table, addition of new shells down the group results in_________. [RRC Group D 17/09/2022 (Afternoon)]

Correct Answer: (d) increase in atomic size and nuclear charge
Solution:

Periodic table discovered by Dmitri Mendeleev (1869). Modern periodic table (18 Groups and 7 Periods) invented by Henry Moseley (1913). The law of the modern Periodic table states that physical and chemical properties of elements are periodic functions of their atomic numbers.

17. Which of the following statements about Mendeleev's periodic table is NOT correct? [RRC Group D 17/09/2022 (Evening)]

Correct Answer: (b) Hydrogen was assigned a fixed position in the Mendeleev's periodic table.
Solution:

Mendeleev placed elements in the order of their atomic weights. Limitations of Mendeleev’s Periodic table: uncertain Position of Hydrogen (because it resembles alkali metals by forming positive ions and resembles halogens by forming diatomic molecules), Position of isotopes (No separate place in the periodic table), Cause of periodicity was not explained, some dissimilar elements have been placed together.

18. Group 2nd elements in the modern periodic table are also known as : [RRC Group D 18/09/2022 (Morning)]

Correct Answer: (a) alkaline earth metals
Solution:

(6 chemical elements, Group-2). Elements - Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). The transition elements or transition metals occupy the short columns in the center of the periodic table between Group 2A and Group 3A.
Elements of group 18 (Inert Gas) are all gases and have completely filled the outermost orbital. These elements are highly stable and don’t react with other elements easily.

19. Which of the following metals has an electronic configuration 2, 8, 4? [RRC Group D 18/09/2022 (Afternoon)]

Correct Answer: (c) Si
Solution:

There are two electrons in the K shell, eight electrons in the L shell and four electrons in the M shell. Total number of electrons is 14. Electronic configuration- The arrangement of electrons around the nucleus of a particular atom or molecule.
Argon (Ar) - Atomic number (18) and Electronic configuration(2,8,8). Phosphorus (P) - Atomic number (15) and Electronic configuration (2,8,5). Chlorine - Atomic number (17) and Electronic configuration (2,8,7).

20. Name the chemist who arranged the elements with similar properties into groups in the year 1817. [RRC Group D 18/09/2022 (Afternoon)]

Correct Answer: (d) JW Dobereiner
Solution:

In 1817, German chemist Johann Wolfgang Dobereiner (first person - started grouping elements on the basis of atomic weight) arranged the elements with similar properties in a group.