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

Total Questions: 50

11. ____ proposed the modern periodic table. [RRB Group D 22/10/2018 (Evening)]

Correct Answer: (d) Moseley
Solution:

In 1913, the English physicist Henry Moseley observed that the atomic number is a more fundamental property of an element than its atomic mass using X-ray spectroscopy.
The Periodic Law owes its development to the Russian chemist, Dmitri Mendeleev (1834-1907) and the German chemist, Lothar Meyer (1830-1895).

12. Elements of Group 1 are called______ [RRB Group D 23/10/2018 (Morning)]

Correct Answer: (b) Alkali metals
Solution:

It includes elements such as Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). They are characterized by having one electron in their outermost shell, which makes them highly reactive. Halogens are elements in Group 17 of the periodic table. Noble gases are elements in Group 18. Alkaline earth metals are elements in Group 2.

13. Which of the following statements is/are true? [RRB Group D 23/10/2018 (Morning)]

A. Out of 114 elements, 32 are non-metals and others are metals.
B. Every ore is a mineral but not every mineral is an ore.

Correct Answer: (d) Only B is true.
Solution:

In the modern periodic table, there are 118 elements . The elements can be divided into Metals and Non-Metals. Non-metals are located at the top right hand side of the Periodic Table.

14. What are the characteristics of rare earth elements? [RRB Group D 23/10/2018 (Morning)]

Correct Answer: (b) Their three outermost shells are incomplete.
Solution:

Their three outermost shells are incomplete. Alkaline Earth Metals - The group 2 elements comprise Beryllium, Magnesium, Calcium, Strontium, Barium and Radium.

15. How many metalloids are there in the fourth period of the modern periodic table ? [RRB Group D 23/10/2018 (Afternoon)]

Correct Answer: (b) 2
Solution:

The two metalloids are: Germanium (Ge), and Arsenic (As). There are 7 metalloids in the modern periodic table. Other 5 are : Boron (B), Silicon (Si), Antimony (Sb), Tellurium (Te), Polonium (Po).

16. Which of the following statements is/are true? [RRB Group D 23/10/2018 (Afternoon)]

A. Out of 114 elements, 22 are non-metals and the others are metals.
B. Every ore is a mineral substance but not every mineral substance is an ore.

Correct Answer: (d) Only B is true
Solution:

In the Periodic Table 118 elements, of which 17 are classified as non-metals. The remaining 101 elements are classified as metals, with some elements exhibiting both metallic and non-metallic properties (metalloids).

17. Which is the first element in the 17th group of the modern periodic table? [RRB Group D 23/10/2018 (Evening)]

Correct Answer: (a) Fluorine
Solution:

Modern Periodic Table : Given By - Henry Moseley (1913). Groups - 18. Periods - 7. Block - 4 (s, p, d, f). From left to right in a period: The atomic size and the metallic character of elements decrease accordingly. Other 17th Group Elements (halogens) - Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At).

18. All the elements in the group of periodic table have the same ________. [RRB Group D 24/10/2018 (Afternoon)]

Correct Answer: (c) Number of valence electrons
Solution:

Valence electrons are the electrons in the outermost shell of an atom, and they play a crucial role in determining the chemical behavior of an element. The elements of the same group have similar chemical properties because they have the same number of valence electrons. For example - Lithium has 1 valence electron and so does Sodium (Na), Potassium (K) and Caesium (Cs).

19. Which of the following is the least electronegative basic element ? [RRB Group D 24/10/2018 (Evening)]

Correct Answer: (a) Cs
Solution:

Fluorine is the most electronegative element in the periodic table. Electronegativity: A qualitative measure of the ability of an atom in a chemical compound to attract shared electrons to itself.
It generally increases across a period from left to right (e.g. from lithium to fluorine) and decreases down a group (e.g. from fluorine to astatine). The electronegativity of any given element is not constant; it depends on the element to which it is bound.

20. In the modern periodic table, what are the basic elements of group 18 (all others except Helium those having eight electrons in their outermost orbit) called? [RRB Group D 24/10/2018 (Evening)]

Correct Answer: (c) Inert gasses
Solution:

(Noble gasses): Group 18 of the periodic table consists of six elements (Helium, Neon, Argon, Krypton, Xenon and Radon). These gasses are chemically unreactive. All the noble gases except radon occur in the atmosphere. All noble gasses have general electronic configuration ns²np⁶ except helium which has 1s² .