71. The hottest part of the gas flame is known as

A. luminous zone
B. dark zone
C. blue zone
D. non-luminous zone

Answer: Option D- non-luminous zone

72. The National Chemical Laboratory is situated in

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

Answer: Option C- Pune

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

Answer: Option C- the number of nucleons

74. Iodine can be separated from a mixture of Iodine and Potassium Chloride by ?
a. Filtration
b. Sublimation
c. Distillation
d. Sedimentation

Answer: Option B- Sublimation

75.Conduction band electrons have more mobility than holes because they are
a. experience collision more frequently
b.experience collision less frequently
c. have negative charge
d. need less energy to move them

Answer: Option B- experience collision less frequently

76. Due to rusting the weight of iron
a. Decreases
b. Increases
c. Remains the same
d. Uncertain

Answer: Option B- Increases

77. The maximum number of covalent formed by nitrogen is

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

Answer: Option D- 4

78. The metal that is usually extracted from sea water is

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

Answer: Option D- Mg

79. 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

Answer: Option C- levigation

80. Sea water contains pH value in the range of ……………………..
1. 8.5
2. 7
3. 6.5-7.5
4. 10.5
5. None of these

Answer – 1- 8.5

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