1. The reference pressure used I the determination of sound pressure level is

1. 1. 20mPa

   
   
   

   2. 20dB

   
   
   

   3. 10mPa

   
   
   

   4. 10dB

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

---

2. Two electrostatic precipitators (ESPs) are in series. The fractional efficiencies of the upstream and downstream ESPs for size d_p are 80% and 65% respectively. What is the overall efficiency of the system for the same d_p?

1. 1. 100%

   
   
   

   2. 93%

   
   
   

   3. 80%

   
   
   

   4. 65%

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Overall efficiency = 80% + 20% × 0.65 = 93%.

   Correct Option: B

   Overall efficiency = 80% + 20% × 0.65 = 93%.

---

---

3. The mean indoor airborne chloroform (CHCl₃) concentration in a room was determined to be 0.4 mg/m³. Use the following data: T = 293 K, P = 1 atmosphere, R = 82.05 × 10^–6 atm. m³/mol-K, Atomic weights: C = 12, H = 1, Cl = 35.5. This concentration expressed in parts per billion (volume basis, ppbv) is equal to

1. 1. 1.00 ppbv

   
   
   

   2. 0.20 ppbv

   
   
   

   3. 0.10 ppbv

   
   
   

   4. 0.08 ppbv

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Molecular weight of CCl₃ = 12 + 1 + 35.5 × 3 = 119.5 g
   

   No. of moles, n =	0.4 μg	=	0.4 × 10-6	= 3.35 × 10-9
   	119.5		119.5

   
   PV = nRT
   

   ∴ V =	nRT	=	3.35 × 10-9 × 82.05 × 10-6 × 293	= 0.08 × 10-9 = 0.08 ppbv
   	P		1

   Correct Option: D

   Molecular weight of CCl₃ = 12 + 1 + 35.5 × 3 = 119.5 g
   

   No. of moles, n =	0.4 μg	=	0.4 × 10-6	= 3.35 × 10-9
   	119.5		119.5

   
   PV = nRT
   

   ∴ V =	nRT	=	3.35 × 10-9 × 82.05 × 10-6 × 293	= 0.08 × 10-9 = 0.08 ppbv
   	P		1

---

4. The cumulative noise power distribution curve at a certain location is given below:
   
   The value of L₄₀ is equal to

1. 1. 90 dBA

   
   
   

   2. 80 dBA

   
   
   

   3. 70 dBA

   
   
   

   4. 60 dBA

   
   
   

---

1. View Hint View Answer Discuss in Forum

   L₄₀ – the noise level which is exceeded 40% of time.
   
   

   Slope of line =	100 - 0	= 2
   	100 - 50

   
   To find L₄₀,
   

   2 =	40 - 0
   	L40 - 50

   
   ∴ L₄₀ = 70 dB.

   Correct Option: C

   L₄₀ – the noise level which is exceeded 40% of time.
   
   

   Slope of line =	100 - 0	= 2
   	100 - 50

   
   To find L₄₀,
   

   2 =	40 - 0
   	L40 - 50

   
   ∴ L₄₀ = 70 dB.

---

---

5. SO₂ and CO adversely affect
   

1. 1. oxygen carrying capacity of blood and functioning of lungs respectively

   
   
   

   2. functioning of the respiratory system and brain respectively

   
   
   

   3. functioning of the respiratory system and oxygen carrying capacity of blood respectively

   
   
   

   4. functioning of air passages and chest respectively

   
   
   

---

1. View Hint View Answer Discuss in Forum

   SO₂ affects functioning of respiratory system. CO reacts with haemoglobin in blood to form carboxy haemoglobin and reduces the oxygen carrying capacity of blood.

   Correct Option: C

   SO₂ affects functioning of respiratory system. CO reacts with haemoglobin in blood to form carboxy haemoglobin and reduces the oxygen carrying capacity of blood.

---