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

Total Questions: 50

41. In the modern periodic table, metals are not included in _______ period. [RRB Group D 11/10/2018 (Evening)]

Correct Answer: (b) 1
Solution:

The first period of the periodic table consists of only two elements, Hydrogen (H) and Helium (He). Metals are typically found on the left side of the periodic table. They exhibit metallic properties such as conductivity, malleability, and ductility.

42. What are the elements of Group 1 of the modern periodic table called? [RRB Group D 12/10/2018 (Morning)]

Correct Answer: (d) alkali metals
Solution:

Group 1 elements, also known as the alkali metals, include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
These metals are highly reactive and are characterized by having one electron in their outermost shell, which they readily lose to form positively charged ions.

43. In the modern periodic table, periods ______ and _____ do not include any metalloids. [RRB Group D 12/10/2018 (Morning)]

Correct Answer: (b) 1,7
Solution:

Metalloids are elements that have properties intermediate between metals and non-metals. Period 1 of the periodic table includes only two elements, hydrogen (H) and helium (He) and Period 7 elements called actinides and It contains 32 elements.

44. _______ elements are present in the fourth period of the periodic table. [RRB Group D 12/10/2018 (Morning)]

Correct Answer: (d) 18
Solution:

The fourth period starts at potassium, and the added electrons fill up the 4s orbital and this period ends at krypton. The sixth period contains 32 elements. The first period contains 2 elements.

45. What is the correct order of the atomic sizes of the elements O, S and Se ? [RRB Group D 12/10/2018 (Evening)]

Correct Answer: (a) Se > S > O
Solution:

In the periodic table, on moving from top to bottom, the size of atomic radii increases. On moving left to right, the size decreases.

46. The atomic numbers of the four basic elements of a period are 11, 13, 16 and 17. The atomic number of the most metallic element in the modern periodic table will be ______. [RRB Group D 15/10/2018 (Morning)]

Correct Answer: (d) 11
Solution:

The element having atomic number 11 is known as sodium (Na). The metallic character in a period decreases from left to right. Hence, the element having the least atomic number in a period will be the highest metallic parent element.

47. In the modern periodic table, bromine is in the _______ period. [RRB Group D 15/10/2018 (Morning)]

Correct Answer: (d) 4
Solution:

A fourth period element begins at Potassium (K) and ends at Krypton (Kr). Bromine is a naturally occurring element that is a liquid at room temperature liquid. Bromine (atomic number 35) is found in the group 17.

48. 'Inert' gasses are in the ___ group. [RRB Group D 15/10/2018 (Morning)]

Correct Answer: (c) VIII A
Solution:

'Inert' gasses, also known as noble gasses. They are part of Group 18 of the modern periodic table. They include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).

49. According to whose classification of elements, the basic elements were arranged in increasing order according to their atomic numbers? [RRB Group D 15/10/2018 (Evening)]

Correct Answer: (a) Mendeleev
Solution:

John Newlands proposed the Law of Octaves, suggesting every eighth element had similar properties. Johann Wolfgang Dobereiner proposed the Law of Triads, grouping elements with related properties in sets of three where the middle element had an average atomic weight of the other two.

50. _______ is used to make perfume. It is also used as a delicious spice. [RRB Group D 15/10/2018 (Evening)]

Correct Answer: (b) Eugenol
Solution:

Cloves are the dried flower buds of the Syzygium aromaticum tree. They have a strong, pungent aroma and flavor due to the presence of eugenol, an essential oil.