Chemistry

61. Atomic number of copper is: [S.S.C. Online CHSL (T-I) 17.03.2020]

(a) 28
(b) 25
(c) 23
(d) 29

Correct Answer: (d) 29

Solution:Copper is a member of group II in the periodic table. Its atomic number is 29. It is also called coin metal because earlier this metal was mainly used in making coins.

62. What is the Atomic Number of the element Einsteinium? [S.S.C. Online CPO S.I. (T-I) 23.11.2020]

(a) 98
(b) 101
(c) 99
(d) 100

Correct Answer: (c) 99

Solution:

The atomic number of the element Einsteinium (Es) is 99.

Einsteinium is a synthetic radioactive element in the actinide series. It was discovered in the debris of the first hydrogen bomb test in 1952 and is named after Albert Einstein. All isotopes of einsteinium are radioactive, and it has no stable isotopes. It is primarily used for scientific research purposes.

63. Which of the following elements has atomic number 87? [S.S.C. Online CPO SI (T-I) 10.11.2022]

(a) Francium
(b) Caesium
(c) Lithium
(d) Rubidium

Correct Answer: (a) Francium

Solution:Francium was discovered in the year 1939 by Marguerite Perey. It is an S block element. Francium (Fr) is a highly radioactive metal. Its atomic number is 87. It is toxic because of its radioactivity. Francium is named after France.

64. What is the symbol of Tin? [S.S.C. Online CHSL (T-I) 12.10.2020]

(a) Ti
(b) Sn
(c) Si
(d) Ta

Correct Answer: (b) Sn

Solution:Tin is a chemical element with the symbol Sn and atomic number 50. It is the main group metal in group 14 of the periodic table.

65. Atomic Number of Hydrogen is _________. [S.S.C. Online CHSL (T-I) 23.01.2017]

(a) 4
(b) 3
(c) 2
(d) 1

Correct Answer: (d) 1

Solution:Hydrogen is the lightest element found in nature. Only 1 proton (+ charged fundamental particle) is found in its nucleus. Therefore, the atomic number of hydrogen is one.

66. What is the approximate atomic mass (u) of hydrogen? [S.S.C. Online MTS (T-I) 08.07.2022]

(a) 12
(b) 4
(c) 1
(d) 14

Correct Answer: (c) 1

Solution:The atomic mass of any element is the sum of the mass of protons and neutrons.
As the mass of 1 proton is, 1.67×10⁻²⁴ g or 1.007 u, therefore this is the mass contained in a hydrogen atom.

67. Which is the most abundant element in the universe? [S.S.C. Online MTS (T-I) 18.09.2017]

(a) Gold
(b) Oxygen
(c) Carbon
(d) Hydrogen

Correct Answer: (d) Hydrogen

Solution:Hydrogen makes up approximately 75% of the baryonic mass of the universe. Helium is the second most abundant, making up about 24%. All other elements constitute only a small fraction (around 1%) of the universe's mass.

68. The substance that loses electrons is called ________. [S.S.C. Online MTS (T-I) 14.10.2017]

(a) oxidizing agent
(b) reducing agent
(c) catalyst
(d) None of these

Correct Answer: (b) reducing agent

Solution:

The substance that loses electrons is called a reducing agent.

Reducing agent: When a substance loses electrons, it causes another substance to gain electrons (and thus be reduced in its oxidation state). Hence, the electron-donating substance is the reducing agent.

69. How many lone pairs are present in nitrogen (N₂) molecule? [S.S.C. Online CHSL (T-I) 31.01.2017]

(a) 1
(b) 3
(c) 4
(d) 2

Correct Answer: (d) 2

Solution:The atomic number of nitrogen is 7. Therefore, an atom of nitrogen has a total of 7 electrons. Therefore, it has 2 electrons in its first orbit and 5 electrons in its outermost orbit. The N, gas molecule has an N ≡ N triplet bond, in which each nitrogen atom completes an octet (8 electrons) in the outermost orbital of each nitrogen atom by providing 3 electrons for the covalent bond. So it is clear that two lone electron pairs are formed in one molecule (N₂) of nitrogen gas.

Draw the electron dot structure of the molecules of (a) Oxygen, and (b) Nitrogen. The atomic numbers of oxygen and nitro