Practice MCQ Questions and answers on Chemistry-GK

71

The National Chemical Laboratory is situated in

A) New Delhi B) Bangalore C) Pune D) Patna

Discuss

Answer & Solution

Answer: Option C

Solution:

National Chemical Laboratory (CSIR-NCL), Pune, established in 1950, is a constituent laboratory of Council of Scientific and Industrial Research (CSIR).

72

Equal masses of oxygen, hydrogen and methane are kept under identical conditions. The ratio of the volumes of gases will be

A) 2 : 16 : 2 B) 2 : 16 : 1 C) 1 : 16 : 2 D) 1 : 1 : 1

Discuss

Answer & Solution

Answer: Option C

Solution:

Convert the mass into moles (use the formula n=m/Mr)
m = mass and Mr = Molecular weights
Molecular weights are 32(Oxygen), 2(Hydrogen), and 16(Methane), respectively.
Since the masses are equal, you can take the mass as x. So, the number of moles would be:
n(O2) = x/32
n(H2) = x/2
n(CH4) = x/16
The ratio of their volumes is (O₂) : (H₂) : (CH₄) = 1 : 16 : 2

73

The mass number of an atom is equal to

A) the number of protons B) the number of protons and electrons C) the number of nucleons D) the number of neutrons

Discuss

Answer & Solution

Answer: Option C

Solution:

The mass number of an atom is equal to the number of nucleons.

74

The maximum number of covalent formed by nitrogen is

A) 1 B) 2 C) 3 D) 4

Discuss

Answer & Solution

Answer: Option D

Solution:

Covalency of an atom in a covalent compound is the number of covalent bonds formed by an atom. Maximum covalency of Nitrogen is 4 (example - ammonium ions).

75

The formula C₆H₅-CO-CH₃ represents

A) Acetone B) Acetic acid C) Acetophenone D) Phenyl acetate

Discuss

Answer & Solution

Answer: Option C

Solution:

The formula C₆H₅-CO-CH₃ represents Acetophenone.

76

The metal that is usually extracted from sea water is

A) Ca B) Na C) K D) Mg

Discuss

Answer & Solution

Answer: Option D

Solution:

In the US, 63% of magnesium production came from seawater and brines during 2015. The metal is extracted from seawater and brines by means of electrolysis, a process that requires the passing of a current through a molten salt.

77

The method of concentrating the ore which makes use of the difference in density between ore and impurities is called

A) liquation B) leaching C) levigation D) magnetic separation

Discuss

Answer & Solution

Answer: Option C

Solution:

Levigation is based on the difference in densities of the metallic ore and gangue particles. Powdered ore is treated with a stream of running water when the lighter gangue particles are washed away and heavier ore particles are left behind.

78

The inert gases are ____ in water.

A) sparingly soluble B) insoluble C) soluble D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

The inert gases are sparingly soluble in water.

79

The molecular formula of phosphorous is

A) P₁ B) P₂ C) P₃ D) P₄

Discuss

Answer & Solution

Answer: Option D

Solution:

The molecular formula of phosphorous is P₄.

80

The names of the scientists, Newlands, Mendeleev, and Meyer are associated with the development of

A) atomic structure B) metallurgy C) periodic table of contents D) discovery of elements

Discuss

Answer & Solution

Answer: Option C

Solution:

They are associated with the development of periodic table of elements. Newland gave the Newland's law of octaves. Mendeleev gave the period law based on atomic mass. Moseley gave the modern period law based on atomic number.