Question 71. Explosions and the resulting fires often kill or trap workers, block avenues of escape, and rapidly generate asphyxiating gases, threatening every worker underground. Explosions in underground mines and surface processing facilities are caused by accumulations of flammable gas and/or combustible dust mixed with air in the presence of an ignition source.  Most of the explosions in mines occur due to the mixing of

Question 72. An atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. In an atom, the order of filling up of the orbitals is governed by

Question 73. Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes. The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond. Diamond is harder than graphite because of

Question 74. Match List I and List II and select the correct answer by using the codes given below.
List I                                   List II
A. Antipyretics        1. Cure allergies
B. Analgesics           2. calm the nerves
C. Tranquilizers       3. relieve pain
D. Antihistamines   4. lower body temperature

Question 75. Match List I and List II and select the correct answer by using the codes given below
List I                     List II
A. Glass           1. Phosphorus
B. Cement       2. Clay
C. Matches      3. Silica
D. Ink               4. Carbon blank
                          5. Cellulose

Question 76. Graphite is known for its use in pencils, where it is commonly called lead. Graphite occurs in metamorphic rocks as a result of the reduction of sedimentary compounds during metamorphism. Consider the following statements regarding graphite
(a) It is an allotrope of carbon.
(b) It is good conductor of heat and electricity.
(c) It can be artificially produced.
Of these statements

Question 77. Assertion (A): Coal-based thermal power stations contribute to acid-rain.
Reason (R): Oxides of carbon are emitted when coal bums. Codes

Question 78. Match List I and List II and select the correct answer by using the codes given below.
List I                                    List II
A. Sodium Palmitate   1. Ore
B. Galena                      2. Fertilizer
C. NPK                           3. Soap
D. Cellulose                  4. Natural polymer

Question 79. Which of the following statements is/are true?
(a) The process of oxidation leads to a gain of electrons.
(b) The process of oxidation leads to a loss of electrons.
(c) The process of reduction leads to a gain of electrons.
(d) The process of reduction leads to a loss of electrons.

Question 80. Match List I and List II and select the correct answer by using the codes given below.
List I (Process)                 List II (Materials Obtained)
A. Hydrogenation      1. Vanaspati
B. Evaporation           2. Ethyl alcohol
C. Distillation             3.Common salt
D. Polymerisation     4.Nylon