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

Total Questions: 50

21. Up to which element was the law of octaves found to be applicable? [RRB JE 22/05/2019 (Afternoon)]

Correct Answer: (b) Calcium
Solution:

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.
It was proposed by John Newlands in 1864. According to this law, elements with similar chemical and physical properties occur at regular intervals of atomic weight. This law was found to be applicable only up to calcium (Ca), after which the pattern breaks down.

22. Which of the following elements has the highest electronegativity? [RRB JE 23/05/2019 (Morning)]

Correct Answer: (c) Fluorine
Solution:

Electronegativity is an atom's tendency to attract electrons to itself in a chemical bond. The electronegativity of atoms decreases as you move from top to bottom down a group in the periodic table.The order of decreasing electronegativity - Fluorine > Chlorine > Bromine > iodine.

23. The horizontal row of the periodic table is called the- [RRB JE 23/05/2019 (Afternoon)]

Correct Answer: (a) Period
Solution:

The Modern Periodic Table contains 7 horizontal rows called periods and 18 vertical columns called Groups. Two rows are separately placed at the bottom of the periodic table for Lanthanides and Actinides.
The whole periodic table is divided into four blocks : s-block (alkali and alkaline earth metals); p-block (metals, non-metals, and metalloids); d-block (transition metals) and f-block (Lanthanides and Actinides series).

24. Which of the following statements about the modern periodic table is NOT correct? [RRB JE 24/05/2019 (Afternoon)]

Correct Answer: (c) Period 1 has only one element
Solution:

Modern Periodic Table (discovered by Henry Moseley in 1913): Electronegativity - From left to right across a period of elements, electronegativity increases. From top to bottom down a group, electronegativity decreases.
Ionization Energy - Increases from left to right on the periodic table. The ionization energy of the elements within a group generally decreases down a group. Helium has the highest ionization energy of all the elements.

25. Based on periodic trends in ionization energy, which element has the highest ionization energy? [RRB JE 24/05/2019 (Afternoon)]

Correct Answer: (c) Helium
Solution:

(He): Group - 18, Period - 1, Block - s, Atomic number - 2, Appearance - Colourless, odourless and non - toxic gas. Ionization energy (Energy required to remove the electron from the outermost shell of an isolated gaseous atom) - Decreases from top to bottom in groups and increases from left to right across a period. Caesium has lowest Ionization energy.
Fluorine (F): Group - 17, Period - 2, Block - p, Atomic number - 9. Nitrogen (N): Group - 15, Period - 2, Block - p, Atomic number - 7. Bromine (Br): Group - 17, Period - 4, Block - p, Atomic number - 35.

26. In a period, elements are arranged in the order of- [RRB JE 25/05/2019 (Morning)]

Correct Answer: (d) Increasing charges in the nucleus
Solution:

In 1913 Henry Moseley had given the modern periodic table. The Modern Periodic Table is classified into the following elements: The s-block includes alkali metals and alkaline earth metals. The p-block contains groups 13 , 14 , 15 , 16, 17 and 18 except for Helium (part of the s block).
The d-block includes Transition elements. The f-block includes Inner Transition Elements. The elements in the modern periodic table are arranged in the order of their increasing atomic numbers.

27. Non-metals like sulphur and chlorine are found on the_______ of the periodic table. [RRB JE 25/05/2019 (Afternoon)]

Correct Answer: (b) Right-hand side
Solution:

Elements on the left side of the periodic table are metals (except for hydrogen). Noble gasses are placed extremely right on the table. The elements in the middle of the periodic table are transition elements.

28. Potassium belongs to which of the following element-family ? [RRB JE 25/05/2019 (Evening)]

Correct Answer: (a) Alkali metals
Solution:

These are the elements found in Group IA of the periodic table (the first column). They are very reactive chemical species that readily lose their one valence electron to form ionic compounds with nonmetals.
Examples - Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr). The alkaline earth family is the second most reactive group. They are found in Group 2 of the periodic table. Examples - Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra).

29. Na, Mg, Al, Si, P, S, Cl and Ar belong to the________period of the modern periodic table. [RRB JE 26/05/2019 (Afternoon)]

Correct Answer: (a) Third
Solution:

Third period elements are also known as Typical elements. The first period has only two elements present in it, they are Hydrogen (H) and Helium (He). The elements of the second period are Lithium (Li), Beryllium (Be), Boron (B), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F) and Neon (Ne).
The elements of fourth period are Potassium (K), Calcium (Ca), Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Germanium (Ge), Arsenic (As), Selenium (Se), Bromine (Br), Krypton (Kr).

30. According to Mendeleev's periodic law, the elements were arranged in the periodic table in the order of- [RRB JE 26/05/2019 (Evening)]

Correct Answer: (a) Increasing atomic masses
Solution:

Dmitri Mendeleev - Father of the Periodic table. Henry Mosely - He arranged the elements in the periodic table according to atomic numbers.