EMS Math-Science Cross-Curricular Lessons 3

Question 1

A facility generates 240 tonnes of hazardous waste annually. If the recycling rate increases from 20% to 35%, how many additional tonnes are diverted from disposal each year?

Accepted Answer

36 tonnes

Answer

Additional diversion = (35% − 20%) × 240 = 15% × 240 = 36 tonnes.

Question 2

The half-life of a radionuclide contaminant in groundwater is 30 years. Approximately what fraction of the original concentration remains after 90 years?

Accepted Answer

1/8

Answer

After 3 half-lives (90 ÷ 30 = 3), the remaining fraction is (½)³ = 1/8.

Question 3

When auditing an industrial cooling tower, an EMS auditor applies the concept of evaporative cooling. Which thermodynamic property primarily drives water loss from the tower?

Accepted Answer

Latent heat of vaporization

Answer

Water evaporates from the cooling tower by absorbing its latent heat of vaporization (~2,260 kJ/kg), which removes heat from the process stream.

Question 4

An EMS corrective action reduces wastewater BOD concentration from 400 mg/L to 60 mg/L. What is the percentage reduction in BOD load?

Accepted Answer

85%

Answer

Reduction = (400 − 60) ÷ 400 × 100 = 340 ÷ 400 × 100 = 85%.

Question 5

A stationary source emits particulate matter at 50 mg/m³ through a stack with a volumetric flow rate of 1,200 m³/hr. What is the mass emission rate in g/hr?

Accepted Answer

60,000 g/hr

Answer

Mass rate = 50 mg/m³ × 1,200 m³/hr = 60,000 mg/hr = 60,000 g/hr... wait: 60,000 mg = 60 g; re-check: 50 mg/m³ × 1,200 m³/hr = 60,000 mg/hr = 60 g/hr — closest listed option is 60,000 mg/hr expressed correctly as 60,000 mg/hr = 60 g/hr; the answer listed as 60,000 g/hr is the value in mg/hr units, but the correct answer in g/hr is 60.

(EMS) Environmental Management Systems Internal Auditor Certification Practice Test

(EMS) Environmental Management Systems Internal Auditor Certification Practice Test

EMS Math-Science Cross-Curricular Lessons 3