91. The process of Galvanization can refer as the process in which:

(a) The steel is melted in high temperature to provide ductility
(b) The metal is dipped in an acid for the fixed length of time, rinsed with water and stored for further use
(c) The metal surface is covered with a thin coat of zinc for protection against corrosion
(d) A thin coat of one metal over the surface of other metal or non metal to alter the surface properly

Answer: (c)

92. As per NFPA (National Fire Protection Association), the background colours of information on health, flammability and reactivity are respectively:
(a) Red, Yellow and Blue
(b) Blue, Yellow and Red
(c) Red, Blue and Yellow
(d) Blue, Red and Yellow

Answer: (d)

93. The EPA Hazardous Waste Number for ignitability is:
(a) D001
(b) D002
(c) D003
(d) D009

Answer: (a)

94. LD50 refers to:
(a) The dose (amount per unit body weight) of a chemical at which first 80 % test animal population dies within a period of time by administering chemicals through ingestion
(b) The concentration of a chemical at which first 50 test animal population dies within a period of time
(c) The dose (amount per unit body weight)of a chemical at which 50% of a test animal population dies within a period of time by administering chemicals through ingestion
(d) The dose (amount per unit body weight) of a chemical at which last 50 test animal population dies within a period of time by administering chemicals through ingestion

Answer: (c)

95. Threshold Limit Values (TLVs) for slightly toxic classes in dilution ventilation is:
(a) <10 ppm
(b) (100−500) ppm
(c) >500 ppm
(d) (10−100) ppm

Answer: (c)

96. International Atomic Energy Agency has recommended the maximum permissible radiation dose limit per week by Roentgen Equivalent Man (REM) as:
(a) 1
(b) 0.5
(c) 0.1
(d) 0.05

Answer: (c)

97. Waste minimization techniques focus primarily on the activities of:
(a) Identification and storage
(b) Recycling and reuse
(c) Source reduction and recycling
(d) Land disposal and record keeping

Answer: (c)

98. Positive pressure respirators are:
1. Self-contained breathing apparatus
2. Air-purifying respirators
3. Supplied-air respirators

(a) 1 only
(b) 2 only
(c) 1 and 2
(d) 1 and 3

Answer: (b)

99. The maximum possible efficiency of Ocean Thermal Energy Conversion (OTEC) system for an electric generating station operating between 30°𝐶 and 5°𝐶 is:
(a) 4 %
(b) 6 %
(c) 8 %
(d) 10 %

Answer: (c)

100. The pollutional effects of discharging raw waste water from a paper mill are:
1. Oxygen depletion in the receiving body of water
2. Presence of undesirable colour, odour and taste in water
3. Reduced photosynthesis
4. Toxicity added to the aquatic life due to the formation of mercaptans, pentachlorophenol and pentachlorophenate

(a) 1, 2, 3 and 4
(b) 1, 2 and 3 only
(c) 1, 3 and 4 only
(d) 2 and 4 only

Answer: (a)