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

Total Questions: 49

21. Which of the following is NOT a noble gas? [RRB ALP Tier - I (13/08/2018) Morning]

Correct Answer: (d) Hydrogen
Solution:

Noble gases (Symbol, Atomic Number, Atomic Mass) - Helium (He, 2, 4), Neon (Ne, 10, 20), Argon (Ar, 18, 39), Krypton (Kr, 36, 83), Xenon (Xe, 54, 131) and Radon (Rn, 86, 222);
Properties - Group 18 Elements, Largest ionization energies, Chemically inert; Extremely stable (Outer shells are full), Small tendency to gain or lose electrons; Low boiling and melting points (Have weak interatomic forces).

22. Which of the following is NOT a radioactive element? [RRB ALP Tier - I (13/08/2018) Afternoon]

Correct Answer: (a) Titanium
Solution:

Radioactivity is the phenomenon of spontaneous emission of particles or waves from the unstable nuclei of some elements. Three types of radioactive emissions: Alpha, Beta and Gamma. Uranium (U), Thorium (Th) and Actinium (Ac) are three Naturally Occurring Radioactive Materials series that contaminate water resources. Uranium(U) - Atomic number 92, Atomic mass: 238u. Uranium is found in metamorphic rocks. Thorium(Th) Atomic number: 90, Atomic mass: 232 u.

23. Atomic numbers of four elements are as follows: F(9) , P(15) Cl(17) Ar(18) Which of the following two elements would be chemically similar? [RRB ALP Tier - I (13/08/2018) Afternoon]

Correct Answer: (d) F and CI
Solution:

Fluorine (F) and chlorine (Cl) are chemically similar because both of them belong to the family of halogens. Fluorine (F): Atomic number 9, Group 17, Electronic configuration 2,7. Chlorine (Cl):
Atomic number 17, Group 17, Electronic configuration 2,8,7. Phosphorus (P): Atomic number 15, Group 15, Electronic configuration 2,8,5. Argon (Ar): Atomic number 18, Group 18, Electronic configuration 2,8,8.

24. Who stated the following law: "The properties of the elements are the periodic function of their atomic masses"? [RRB ALP Tier - I (13/08/2018) Evening]

Correct Answer: (b) Mendeleev
Solution:

Mendeleev (Father of the Periodic table) {(63 elements) 1st - Hydrogen (H) and Last - Uranium (U)}: He arranged elements in periods (horizontal rows) and groups (vertical columns) in the increasing order of atomic weights. Limitations - Isotopes haven't been given a separate place in the periodic table, Mendeleev could not explain the cause of periodicity separation of similar elements and Increase in atomic mass was not regular while moving from one element to another. Merits - Some gaps were left for the elements yet to be discovered.

25. Which is the first metallic element in the Modern Periodic Table? (Periodic Table) [RRB ALP Tier - I (14/08/2018) Morning]

Correct Answer: (c) Li
Solution:

Li (Lithium) - Atomic number - 3, Atomic mass - 7, Discoverer by : Johan August Arfwedson. H (Hydrogen) - Atomic number - 1, Atomic mass - 1, Discovered by - Henry Cavendish.
Na (Sodium) - Atomic number - 11, Atomic mass - 22, Discovered by - Humphry Davy. He (Helium) - Atomic number - 2, Atomic mass - 4, Discovered by - Jules Janssen.

26. In the modern periodic table, which of the two periods contain 8 elements each? [RRB ALP Tier - I (14/08/2018) Afternoon]

Correct Answer: (c) 2 and 3
Solution:

There are seven periods in the periodic table, with each one beginning at the far left. Period 1 has only two elements (Hydrogen and Helium), while periods 2 and 3 have 8 elements. Periods 4 and 5 have 18 elements. Periods 6 and 7 have 32 elements. There are a total of 18 groups in the periodic table.

27. How are elements arranged in the Modern Periodic Table? [RRB ALP Tier - I (14/08/2018) Evening]

Correct Answer: (a) In the increasing order of their Atomic Number
Solution:

The Modern Periodic (given by Henry Moseley) Table arranges the elements in the order of their atomic numbers in seven horizontal rows (periods) and eighteen vertical columns (groups or families).
Mendeleev's periodic law states that the chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic weights.

28. Metals are placed on which side of the Modern Periodic Table? [RRB ALP Tier - I (17/08/2018) Morning]

Correct Answer: (b) Left side
Solution:

The groups on the left side contain elements that have very few electrons in their outermost shell. These elements prefer donating electrons in order to obtain a noble gas configuration.
Modern periodic table: horizontal rows - periods, vertical rows - groups; Right side - nonmetals, leftmost - alkali metals. chemical elements are arranged from left to right and top to bottom in order of increasing atomic number. Father of the periodic table - Dametree Mandeleev.

29. Iron which resembles Cobalt and Nickel in properties has been placed far away from these elements. This was one of the limitations of: [RRB ALP Tier - I (17/08/2018) Afternoon]

Correct Answer: (d) Newlands' law of octaves
Solution:

The 56 elements that were then known were examined in 1864 by British scientist John Newlands. Limitation of Newland law of octaves - It was applicable to only lighter elements having atomic masses upto 40u, i.e, upto calcium.
Those elements that were discovered after Newland's octaves did not follow the law of octaves. Some similar elements have been separated from one another while some dissimilar elements have been placed in the same column.

30. Non-metallic character increases from______(Periodic Table) [RRB ALP Tier - I (17/08/2018) Afternoon]

Correct Answer: (b) Sodium to Chlorine
Solution:

Metallic character refers to how readily an atom loses an electron. Conversely, The non-metallic character is concerned with how readily an atom gains Electrons. Sodium and chlorine belong to the 3rd period and while sodium is in group 1, chlorine is in group 9, therefore when we move from sodium (left) to chlorine (right), the non-metallic character increases.