Environmental Health Practice Questions

Q: Kata thermometer is used for recording :

Low air velocities. ***Low air velocities*** - A **Kata thermometer** is a specialized alcohol thermometer designed to measure **cooling power** and **air velocity** in various environments. - It works by being heated to a specific temperature and then measuring the time it takes to cool down, which is influenced by air movement. *Relative humidity of the air* - **Relative humidity** is typically measured using a **psychrometer** (a wet-bulb and dry-bulb thermometer) or a **hygrometer**. - The Kata thermometer does not directly measure humidity; rather, humidity can indirectly influence its cooling rate. *Mean radiant temperature* - **Mean radiant temperature** is measured using a **globe thermometer**, which uses a temperature sensor inside a black globe. - The Kata thermometer is not designed for this purpose, as it primarily assesses air movement and cooling power. *Maximum and minimum temperature* - **Maximum and minimum temperatures** are typically recorded by a **Six's thermometer** or conventional mercury/alcohol thermometers. - While a Kata thermometer has a temperature scale, its primary use is not for simple maximum/minimum readings but for measuring air velocity and cooling.

Q: During the process of chlorination of water, the disinfecting action of chlorine is due to the formation of

Hypochlorous acid and hypochlorite ions. ***Hypochlorous acid and hypochlorite ions*** - When **chlorine gas** (Cl2) is added to water, it rapidly reacts to form **hypochlorous acid (HOCl)** and **hydrochloric acid (HCl)**. - Hypochlorous acid then partially dissociates into **hypochlorite ions (OCl-)** depending on the pH of the water; both HOCl and OCl- are potent disinfectants, with HOCl being 80-100 times more effective. *Chlorine gas only* - While chlorine gas is the starting material for chlorination, it is not the primary disinfectant in water. - Chlorine gas reacts with water to form other active disinfectant compounds; it does not directly act as a disinfectant at significant levels in water treatment. *Hydrochloric acid only* - **Hydrochloric acid (HCl)** is a byproduct of the reaction of chlorine with water, but it is not the active disinfecting agent. - HCl contributes to the lowering of pH but does not possess the strong antimicrobial properties of hypochlorous acid or hypochlorite ions. *Hypochlorous acid only* - **Hypochlorous acid (HOCl)** is indeed a very strong disinfectant and a critical component of water chlorination. - However, in typical water treatment pH ranges, a significant proportion of HOCl also dissociates into **hypochlorite ions (OCl-)**, which also contribute to the disinfecting action, making the combined effect the primary mechanism.

Q: Horrock's apparatus is used to measure :

Free chlorine. ***Free chlorine*** - Horrock's apparatus is a device specifically designed for the **estimation of residual free chlorine** in treated water. - It uses a tablet and a comparator system to visually match the color produced with a standard scale, indicating the free chlorine level. *Free and combined chlorine* - This apparatus is specifically designed for **free chlorine** and does not directly measure combined chlorine. - While total chlorine (free + combined) can be inferred through subsequent tests, the Horrock's apparatus itself isolates free chlorine. *Chlorine demand* - **Chlorine demand** refers to the amount of chlorine used up by impurities in water before a residual begins to form, and is not directly measured by Horrock's apparatus. - It is determined by knowing the added chlorine dose and the residual chlorine remaining after a contact period. *Combined chlorine* - **Combined chlorine** refers to chlorine that has reacted with ammonia or organic nitrogen compounds, forming chloramines, and is not the primary measurement of Horrock's apparatus. - Measuring combined chlorine typically involves different methods or calculations after determining free and total chlorine.

Q: The method of choice for purification of highly polluted water on a large scale is :

Super-chlorination followed by de-chlorination. ***Super-chlorination followed by de-chlorination*** - **Super-chlorination** involves adding a very large dose of chlorine to water to ensure the destruction of all pathogenic microorganisms and removal of organic matter, making it suitable for **highly polluted water**. - **De-chlorination** is then necessary to remove residual chlorine, as high levels can be harmful and impart an unpleasant taste and odor. *Chlorination only* - While effective for disinfection, **chlorination alone** might not be sufficient to purify highly polluted water with significant organic load or diverse pathogens. - Excessive chlorine content without subsequent de-chlorination can lead to **undesirable by-products** and make the water unpalatable. *Ultraviolet light treatment* - **UV light treatment** is an effective disinfectant that inactivates microorganisms, but it does not remove suspended solids, dissolved organic matter, or chemical pollutants often found in **highly polluted water**. - Its efficacy can be reduced by water turbidity, which is common in highly contaminated sources, requiring extensive pre-treatment. *Boiling and chlorination* - **Boiling** is effective for killing most microorganisms but is impractical and energy-intensive for **large-scale water purification**. - **Chlorination** after boiling would still be needed for residual disinfection, but the combination isn't the method of choice for the high volumes typical of municipal water treatment of highly polluted sources.

Q: Discarded tablets are disposed of in :

Yellow plastic bag. ***Yellow plastic bag*** - The **yellow plastic bag** is designated for **pharmaceutical waste**, which includes discarded and expired medications like tablets, as per **Bio-Medical Waste Management Rules, 2016 (India)**. - This color coding ensures that such waste is handled safely and disposed of according to **specific environmental regulations** to prevent pollution and health hazards. - Yellow bags are used for infectious waste, anatomical waste, soiled waste, expired medicines, and chemical waste. *Black plastic bag* - **Black plastic bags** are used for **general non-hazardous waste** from administrative and housekeeping areas that do not pose infection risk. - Discarding pharmaceuticals in black bags is inappropriate due to the potential for environmental contamination and health hazards. *Red plastic bag* - **Red plastic bags** are for **contaminated waste (recyclable)**, such as tubing, catheters, IV sets, and blood bags. - While some pharmaceutical waste can be hazardous, general discarded tablets are specifically categorized under yellow bag waste, not red. *Blue/White plastic bag* - **Blue or white plastic bags** are used for **sharp waste** including needles, syringes with needles, scalpels, and blades. - Discarded tablets do not fall under sharp waste category and must be disposed in yellow bags as per BMW Rules.

Q: Consider the following : 1. Magnesium Sulphate 2. Calcium bicarbonate 3. Calcium Sulphate 4. Magnesium bicarbonate Hardness of water relates to the presence of which of the above?

1, 2, 3 and 4. **Correct Answer: 1, 2, 3 and 4** **Hardness of water** is caused by the presence of dissolved multivalent metallic cations, primarily **calcium (Ca²⁺)** and **magnesium (Mg²⁺)** ions. These ions combine with various anions to form compounds that cause water hardness: - **Magnesium sulfate (MgSO₄)** - Causes **permanent hardness** (cannot be removed by boiling) - **Calcium bicarbonate (Ca(HCO₃)₂)** - Causes **temporary hardness** (can be removed by boiling) - **Calcium sulfate (CaSO₄)** - Causes **permanent hardness** - **Magnesium bicarbonate (Mg(HCO₃)₂)** - Causes **temporary hardness** **Therefore, all four compounds (1, 2, 3, and 4) contribute to water hardness.** *Why other options are incorrect:* *1, 2 and 3 only* - Incorrectly excludes **magnesium bicarbonate**, which is a significant contributor to temporary hardness *2, 3 and 4 only* - Incorrectly excludes **magnesium sulfate**, which contributes to permanent hardness *1 and 4 only* - Incorrectly omits **calcium bicarbonate** and **calcium sulfate**, which are major contributors to both temporary and permanent hardness

Q: Which of the following insecticides is a natural contact poison?

Rotenone. ***Rotenone*** - **Rotenone** is a naturally occurring plant-derived insecticide, traditionally used as a **contact poison** and **stomach poison**. - It is effective against a broad spectrum of insects and works by inhibiting **electron transport** in the mitochondria, disrupting cellular respiration. *Propoxur* - **Propoxur** is a **synthetic carbamate insecticide**, not a natural one. - It acts primarily as a **cholinesterase inhibitor**, interfering with nervous system function. *Carbaryl* - **Carbaryl** is a **synthetic carbamate insecticide**, derived from carbamic acid, not a natural product. - Its mechanism of action involves **reversible inhibition of acetylcholinesterase**, leading to nerve overstimulation. *Lindane* - **Lindane** is an **organochlorine insecticide**, which is a synthetic compound, not naturally occurring. - It acts as a **neurotoxin**, primarily by interfering with **GABA-gated chloride channels** in the insect's nervous system.

Q: What is the correct order of the steps in the rapid sand filtration process for water purification?

Alum mixing – flocculation – sedimentation – filtration. ***Alum mixing – flocculation – sedimentation – filtration*** - This sequence represents the established steps in conventional **rapid sand filtration**, where each stage plays a crucial role in removing impurities. - **Alum mixing** (coagulation) destabilizes particles, **flocculation** consolidates them, **sedimentation** removes larger flocs, and **filtration** traps remaining fine particles. *Sedimentation – alum mixing – flocculation – filtration* - **Sedimentation** occurs *after* coagulation and flocculation, as these processes are needed to create larger, settleable particles. - Starting with sedimentation before preparing the water for efficient particle removal would be ineffective. *Alum mixing – sedimentation – flocculation – filtration* - **Flocculation** (the gentle stirring to form larger flocs) must happen *after* alum mixing (coagulation) and *before* sedimentation. - Placing sedimentation before flocculation would lead to poor particle removal as the flocs would not have fully formed. *Flocculation – alum mixing – sedimentation – filtration* - **Alum mixing** (coagulation) is the initial step to destabilize particles, which then allows for effective flocculation. - Attempting flocculation before coagulation would be ineffective as the particles would not be prepared to aggregate.

Q: Which of the following tests is NOT used for checking quality of pasteurisation of milk?

Orthotoluidine test. ### ***Orthotoludine test*** * The **Orthotoluidine test** is used to detect residual **chlorine** in drinking water. * It is not employed to assess the quality of pasteurization in milk, which focuses on enzyme inactivation and microbial reduction. ### *Phosphatase test* * The **phosphatase test** is the most widely accepted and reliable method for checking the adequacy of **pasteurization** in milk. * It works by detecting the activity of **alkaline phosphatase**, an enzyme naturally present in raw milk that is destroyed at pasteurization temperatures. ### *Coliform count* * The **coliform count** is an indicator of **post-pasteurization contamination** or inadequate sanitation. * While not a direct measure of the pasteurization process itself, a high coliform count suggests a failure in hygiene after heating, indicating poor overall quality control. ### *Standard Plate count* * The **Standard Plate Count (SPC)**, also known as the **aerobic plate count**, measures the total number of viable microorganisms in milk. * A reduction in SPC after pasteurization indicates the effectiveness of the heat treatment in killing bacteria, making it an indirect measure of pasteurization efficiency and overall microbial quality.

Q: Biomedical waste from a yellow plastic bag is disposed by:

Incineration. ***Incineration*** - **Yellow bags** are designated for **highly infectious waste**, body parts, anatomical waste, and cytotoxic drugs. - **Incineration** is the preferred method for this waste category due to its ability to completely destroy pathogens and reduce waste volume. *Chemical treatment* - This method is typically used for **liquid infectious waste** or for disinfection of certain instruments. - It's not the primary disposal method for the solid, highly infectious waste found in yellow bags. *Microwaving* - **Microwaving** is a thermal disinfection method used for certain types of infectious waste, especially those containing plastics. - It is generally not suitable for **anatomical waste** or large quantities of highly infectious waste like those in yellow bags. *Autoclaving* - **Autoclaving** is a moist heat sterilization method primarily used for items in **red or blue bags**, such as contaminated plastics, cultures, and sharps (after shredding). - It is not the recommended disposal method for anatomical waste or cytotoxic waste collected in yellow bags.

Question 1

Kata thermometer is used for recording :

Accepted Answer

Low air velocities

Answer

Relative humidity of the air

Answer

Mean radiant temperature

Answer

Maximum and minimum temperature

Question 2

During the process of chlorination of water, the disinfecting action of chlorine is due to the formation of

Accepted Answer

Hypochlorous acid and hypochlorite ions

Answer

Chlorine gas only

Answer

Hydrochloric acid only

Answer

Hypochlorous acid only

Question 3

Horrock's apparatus is used to measure :

Accepted Answer

Free chlorine

Answer

Free and combined chlorine

Answer

Chlorine demand

Answer

Combined chlorine

Question 4

The method of choice for purification of highly polluted water on a large scale is :

Accepted Answer

Super-chlorination followed by de-chlorination

Answer

Chlorination only

Answer

Ultraviolet light treatment

Answer

Boiling and chlorination

Question 5

Discarded tablets are disposed of in :

Accepted Answer

Yellow plastic bag

Answer

Black plastic bag

Answer

Red plastic bag

Answer

Blue plastic bag

Question 6

Consider the following :

1. Magnesium Sulphate
2. Calcium bicarbonate
3. Calcium Sulphate
4. Magnesium bicarbonate

Hardness of water relates to the presence of which of the above?

Accepted Answer

1, 2, 3 and 4

Answer

1, 2 and 3 only

Answer

2, 3 and 4 only

Answer

1 and 4 only

Question 7

Which of the following insecticides is a natural contact poison?

Accepted Answer

Rotenone

Answer

Propoxur

Answer

Carbaryl

Answer

Lindane

Question 8

What is the correct order of the steps in the rapid sand filtration process for water purification?

Accepted Answer

Alum mixing – flocculation – sedimentation – filtration

Answer

Sedimentation – alum mixing – flocculation – filtration

Answer

Alum mixing – sedimentation – flocculation – filtration

Answer

Flocculation – alum mixing – sedimentation – filtration

Question 9

Which of the following tests is NOT used for checking quality of pasteurisation of milk?

Accepted Answer

Orthotoluidine test

Answer

Phosphatase test

Answer

Coliform count

Answer

Standard Plate count

Question 10

Biomedical waste from a yellow plastic bag is disposed by:

Accepted Answer

Incineration

Answer

Chemical treatment

Answer

Microwaving

Answer

Autoclaving

Environmental Health — MCQs

Environmental Health — MCQs

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