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

Total Questions: 50

21. __________ is the only non-metal present in Group 1 of the Modern Periodic Table. [RRB Group D 22/09/2018 (Evening)]

Correct Answer: (d) Hydrogen
Solution:

Hydrogen (H) - The lightest element. Atomic number - 1, atomic mass - 1.00784 u, discovered by - Henry Cavendish. Cobalt (Co) : Atomic number - 27, Metal, Group - 9, Period - 4, Block - d block. Potassium (K) : Atomic number - 19, Metal, Group - 1, Period - 4, Block - S block. Rubidium : Atomic number - 37, Metal, Group - 1, Period - 5, Block - S block.

22. The element of the Lanthanide series having the atomic number 58 is ________ . [RRB Group D 22/09/2018 (Evening)]

Correct Answer: (a) Cerium
Solution:

Cerium (second element in the lanthanide series) - Other elements of Lanthanide series with their atomic number (14 elements) : Cerium (Ce) - 58, Praseodymium (Pr) - 59, Neodymium (Nd) - 60, Promethium (Pm) - 61, Samarium (Sm) - 62, Europium (Eu) - 63, Gadolinium (Gd) - 64, Terbium (Tb) - 65, Dysprosium (Dy) - 66, Holmium (Ho) - 67, Erbium (Er) - 68, Thulium (Tm) - 69, Ytterbium (Yb) - 70 and Lutetium (Lu) - 71.

23. ______ is NOT an actinoid. [RRB Group D 22/09/2018 (Evening)]

Correct Answer: (a) Terbium
Solution:

A fairly electropositive metal that reacts with water, evolving hydrogen gas. It is the ninth member of the lanthanide series. Atomic number - 65. Actinoid elements (15 elements) - Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Californium (Cf), Einsteinium (Es), Fermium (Fm), Mendelevium (Md), Nobelium (No) and Lawrencium (Lr).

24. Ce-58 is a member of _______ block of elements. [RRB Group D 23/09/2018 (Afternoon)]

Correct Answer: (c) f
Solution:

Cerium (Ce) is the second member of the Lanthanide series. Blocks and Elements : s-Block - (Alkali Metals and Alkaline Earth Metals), p-Block (Metals, Metalloids, Non-Metals, Noble gases), d-Block (Transition elements), f-Block (Lanthanoids and Actinoids).

25. Who predicted the existence of some yet to be discovered elements on the basis of gaps in his periodic table? [RRB Group D 23/09/2018 (Afternoon)]

Correct Answer: (a) Mendeleev
Solution:

Mendeleev’s Periodic Law - The physical and chemical properties of the elements are a periodic function of their atomic masses. Dobereiner’s Law of Triads - The arithmetic mean of the atomic masses of the first and third element in a triad would be approximately equal to the atomic mass of the second element in that triad.

26. Which of the following three elements have filled outermost shell? [RRB Group D 23/09/2018 (Afternoon)]

Correct Answer: (d) Helium (He), Neon (Ne), Argon (Ar)
Solution:

These all are from the Noble gas (Inert gases) family and belong to Group 18. Properties of Noble Gas - Fairly non-reactive, filled Valence shell, High ionization enthalpy, Low boiling points, colorless and odorless. Other noble gases - Krypton (Kr, 36), Xenon (Xe, 54), and Radioactive radon (Rn, 86).

27. Electronegativity when going from fluorine to chlorine, bromine and then iodine ______. [RRB Group D 24/09/2018 (Morning)]

Correct Answer: (a) becomes less
Solution:

Electronegativity is defined as the ability of an atom in a chemical compound to attract a shared electron to itself. The electronegativity increases across the period from left to right. Pauling Scale is widely used to measure electronegativity.

28. Atomic number of magnesium is 12, find its valency? [RRB Group D 24/09/2018 (Morning)]

Correct Answer: (c) +2
Solution:

Valency is the number of electrons an atom loses, gains or shares with other atoms in order to get a stable configuration. Magnesium has 12 electrons, with the electronic configuration of 2, 8, 2.
To attain the nearest noble gas configuration, magnesium loses two electrons from its outermost shell, forming a positive ion with a charge of +2.

29. Group ___________ of the modern periodic table has only 7 elements. [RRB Group D 24/09/2018 (Afternoon)]

Correct Answer: (a) 1
Solution:

The modern periodic table has 18 groups and 7 periods. Groups 1 and 2 are known as the alkali metals and alkaline earth metals, respectively. Groups 3-12 are transition metals, which often exhibit multiple oxidation states. Group 17 is the halogens, and Group 18 is the noble gasses.

30. Californium is a member of: [RRB Group D 24/09/2018 (Afternoon)]

Correct Answer: (c) Actinide series
Solution:

Other elements (Atomic number) in the Actinides Groups: Actinium (89), Thorium (90), Protactinium (91), Uranium (92), Neptunium (93), Plutonium (94), Americium (95), Curium (96), Berkelium (97), Californium (98), Einsteinium (91), Fermium (100), Mendelevium (101), Nobelium (102), and Lawrencium (103).