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

Total Questions: 50

11. The atomic mass of calcium is_______. [RRB Group D 01/10/2018 (Morning)]

Correct Answer: (d) 40
Solution:

Atomic number of calcium (Ca) is 20. It is the most abundant mineral in the body. It is the 5th most abundant element in the Earth's crust, present at a level of about 3 per cent in the oceans and soil.

12. Which of the following classifications was based on atomic masses? [RRB Group D 01/10/2018 (Morning)]

Correct Answer: (c) Dobereiner, Newlands and Mendeleev
Solution:

In Mendeleev’s Periodic Table, the elements are arranged in the order of their atomic masses. In Newland’s Law of Octaves, the elements are arranged in the order of their increasing atomic masses and every 8th element has similar properties. Dobereiner’s Triads have elements with similar properties.

13. The classification of elements done by which of the following inspires the discovery of new elements? [RRB Group D 01/10/2018 (Afternoon)]

Correct Answer: (c) Mendeleev
Solution:

He arranged the elements in his periodic table on the basis of atomic masses. Dmitri Mendeleev is known as the father of the periodic table. The number of elements discovered during his time was 63.

14. The electronic configuration of hydrogen is similar to which of the following? [RRB Group D 01/10/2018 (Afternoon)]

Correct Answer: (c) Alkali metals
Solution:

Alkali metals - It belongs to the s-block elements and readily loses electrons, making them count among the most reactive elements on earth.
Hydrogen is a very special element of the periodic table and doesn't belong to any group. While hydrogen sits in Group I (alkali metal), it is NOT an alkali metal.

15. Element X forms an oxide, whose formula is X₂O₃ , Element X is most likely to be in the same group as _______ in the periodic table. [RRB Group D 01/10/2018 (Afternoon)]

Correct Answer: (b) Aluminum
Solution:

The oxide formula X₂O₃ suggests that element X forms 3 bonds with oxygen. This indicates that X needs 3 electrons to achieve a stable noble gas configuration. Group 13 elements (including Boron, Aluminum, Gallium, Indium, and Thallium) all have 3 valence electrons in their outermost shell.

16. Which of the following states that "properties of elements are a periodic function of their atomic number"? [RRB Group D 01/10/2018 (Evening)]

Correct Answer: (b) Modern periodic law
Solution:

Modern periodic law was proposed by Henry Moseley in 1913. Dobereiner Triads - The atomic weight of the middle element is nearly the same as the average of the atomic weights of other two elements.
Newland's Law of Octaves - When Elements are arranged in increasing order of Atomic Mass, the properties of every eighth element starting from any element are a repetition of the properties of the starting Element. Mendeleev's periodic law - It states that ‘the properties of elements are the periodic function of their atomic mass’.

17. There are _______ metalloids in the modern periodic table [RRB Group D 03/10/2018 (Morning)]

Correct Answer: (c) 7
Solution:

Metalloids: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Polonium (Po).
Metalloids: Chemical elements whose physical and chemical properties fall in between the metal and non-metal categories. They are brittle and can form alloys with metals.

18. Which is the only non-metal placed at the left side of the Modern Periodic Table ? [RRB Group D 03/10/2018 (Morning)]

Correct Answer: (a) Hydrogen
Solution:

Hydrogen (H) : Atomic number - 1, Block - S block. It is the lightest element in the periodic table. Carbon forms covalent bonds with itself and other elements such as hydrogen, oxygen, sulfur, nitrogen and chlorine.
Atomic number - 6. Group - 14. Neon (Ne) : Neon is a colorless, odorless, inert monatomic gas. Atomic number - 10. Helium (He) - Noble gas colorless, odorless, tasteless, non-toxic, inert, monatomic gas. Atomic number - 2.

19. ______element is represented by the given symbol. [RRB Group D 03/10/2018 (Morning)]

Correct Answer: (b) Mercury
Solution:

Atomic number - 80. It is known as quicksilver, and was formerly named hydrargyrum. All metals except mercury exist as solids at room temperature. gallium and caesium have very low melting points. These two metals will melt if you keep them on your palm. Alkali metals (lithium, sodium, potassium) are so soft that they can be cut with a knife.

20. An element has electronic configuration 2, 8, 6. It belongs to _________. [RRB Group D 03/10/2018 (Afternoon)]

Correct Answer: (b) 16 group and 3 period
Solution:

{electronic configuration of Sulphur (16) - 2, 8, 6 }. The oxygen family (chalcogens), consists of the elements found in Group 16; Elements with atomic number: oxygen (O, 8), Sulfur (S,16), Selenium (Se, 34), Tellurium (Te, 52), Polonium (Po, 84).
The third period of the Modern periodic table contains eight elements: Sodium (Na, 11), Magnesium (Mg,12), Aluminium (Al, 13), Silicon (Si, 14), Phosphorus (P, 15), Sulfur (S, 16), Chlorine (Cl, 17), Argon (Ar, 18).