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

Total Questions: 50

31. Which of the following is known as wonder element ? [RRB Group D 29/10/2018 (Evening)]

Correct Answer: (d) Titanium (Ti)
Solution:

Titanium(Ti) is known for its high strength, lightweight, and exceptional corrosion resistance. Atomic number is 22.
Usage - Aerospace industry, Automobile Industry, the Marine Engineering. Gold (Au) is the most malleable and ductile metal.
Atomic number is 79. Mercury (Hg) is called quicksilver. It is the only metal that is liquid at room temperature. Atomic number is 80.
Lithium (Li) is a soft, silvery metal and it has the lowest density of all metals. Atomic number is 3. Usages - Rechargeable batteries for mobile phones, and electric vehicles.

32. Fill in the blanks using the correct option for the following statement from the given options. ______ has the greatest tendency to lose electrons. [RRB Group D 30/10/2018 (Morning)]

Correct Answer: (c) Fe
Solution:

Ionization energy: Minimum energy needed to remove the outermost electron from an isolated gas-phase atom. Atomic radius: Total distance from the nucleus of an atom to the outermost orbital of its electron.
Ionization Potential α  1/𝐴𝑡𝑜𝑚𝑖𝑐𝑅𝑎𝑑𝑖𝑢𝑠.

33. The group which shows the correct order of first ionization potential is: [RRB Group D 30/10/2018 (Afternoon)]

Correct Answer: (d) Be > Mg > Ca
Solution:

The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase. First ionization energy - The energy to go from neutral atoms to cations with a 1+ charge. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period.

34. The second group of elements is called: [RRB Group D 31/10/2018 (Morning)]

Correct Answer: (d) alkaline earth metals
Solution:

These elements include: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). Properties of alkaline earth metals: They are shiny in appearance, They have low densities, They readily lose their two outermost electrons and form cations with a 2⁺ charge.

35. The electronic configuration of an element is 1s² 2s² 2p⁶ 3s² 3p³ . What is the atomic number of the element that is just below the above element in the periodic table? [RRB Group D 31/10/2018 (Afternoon)]

Correct Answer: (b) 33
Solution:

The electronic configuration 1s² 2s² 2p⁶ 3s² 3p³ represents phosphorus with atomic number 15. Arsenic is just below phosphorus in the periodic table. Its atomic number is 33.

36. D block elements are found in: [RRB Group D 31/10/2018 (Afternoon)]

Correct Answer: (a) between 3 to 12
Solution:

d-Block elements occupy the middle portion of the periodic table i.e. between s and pblock elements. They include elements from groups 3 to 12. In these elements the outermost shell contains one or two electrons in their outermost i.e, ns orbital but the last electron enters into the inner d-subshell i.e. (n-l) d orbital. The elements of the d-block are metallic in nature. Transition elements are elements in which the d subshell is partially filled either in atomic state or in ionic state.

37. Which of the following elements in the fourth period has the smallest atomic radius ? [RRB Group D 31/10/2018 (Evening)]

Correct Answer: (d) Bromine
Solution:

The atomic size decreases along the period towards the right but the noble gases are larger than halogens. So the smallest element of the period is the halogen. Fluorine (F₉) is the second period element. Chlorine (Cl₁₇) is the third period element. Iodine (I₅₃) is the fifth period element.

38. The outermost electronic configuration of the most electronegative element is: [RRB Group D 1/11/2018 (Evening)]

Correct Answer: (c) ns²np⁵
Solution:

Electronegativity: This is a measure of an atom's ability to attract electrons towards itself in a chemical bond. Periodic trends: Generally, electronegativity increases across a period from left to right and decreases down a group.

39. In the modern periodic table, which period has 32 elements ? [RRB Group D 2/11/2018 (Morning)]

Correct Answer: (d) Period 6
Solution:

The elements in each period of the periodic table : Period 1 has 2 elements (Hydrogen and Helium), Period 2 (8 elements), Period 3 (8 elements), Period 4 (18 elements), Period 5 (18 elements), Period 6 and 7 (32 elements).

40. Which is the only non-metal placed at the left side of the Modern Periodic Table ? [RRB Group D 2/11/2018 (Evening)]

Correct Answer: (b) Hydrogen
Solution:

Hydrogen (H) - It is a colorless, odorless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements. It is the lightest element in the periodic table. Dmitri Mendeleev - Father of periodic table of elements.