Environmental Health Practice Questions

Q: What is the reagent used in Horrock's apparatus for determining the chlorine demand of water?

Orthotoluidine. ***Orthotoluidine*** - **Orthotoluidine** is the standard reagent used in **Horrock's apparatus** for determining the **chlorine demand of water**. - It reacts with chlorine to produce a **yellow color**, with the intensity proportional to the residual chlorine concentration. - This allows determination of the **minimum chlorine dose** required to maintain adequate residual chlorine after the chlorine demand is satisfied. - Horrock's apparatus is specifically designed to use orthotoluidine for this chlorine demand testing. *Starch iodide indicator* - **Starch iodide** is used to detect the presence of **free residual chlorine** and produces a **blue color**. - While useful for chlorine detection, it is **not the specific reagent** used in Horrock's apparatus for chlorine demand determination. - It is more commonly used in qualitative testing rather than the quantitative assessment provided by Horrock's method. *Methylene blue* - **Methylene blue** is a **redox indicator** and stain used in microbiology. - It has **no role** in Horrock's apparatus or chlorine demand testing. *Sodium bicarbonate* - **Sodium bicarbonate** is a **buffering agent** used to adjust pH in various processes. - It is **not used as a reagent** for detecting or measuring chlorine in Horrock's apparatus.

Q: The minimum recommended concentration of free chlorine in drinking water at the end of one hour (mg/L) is:

0.5. ***0.5*** - This is the **minimum recommended free chlorine residual** to ensure adequate disinfection and provide a protective residual in the distribution system for at least one hour. - A concentration of **0.5 mg/L** ensures sustained antimicrobial activity against various pathogens. *0.1* - A free chlorine residual of **0.1 mg/L** is generally considered too low to provide sustained disinfection over one hour. - This level may not be sufficient to safeguard against potential contamination or bacterial regrowth in the distribution network. *1* - While a **1 mg/L** free chlorine concentration would provide robust disinfection, it is higher than the minimum recommended level. - Such a concentration might lead to increased taste and odor complaints in drinking water without significantly adding to the required public health protection. *1.5* - A concentration of **1.5 mg/L** free chlorine is considerably higher than the minimum requirement for drinking water residual. - This level is often used for specific purposes like **disinfection of newly laid pipes** or during emergencies, rather than as a routine residual for consumer supply due to potential adverse effects on taste and materials.

Q: According to WHO guidelines for water, sanitation and hygiene in schools, what is the recommended minimum number of toilet facilities (urinals and latrines combined) per students in a school setting?

60,100. ***60,100*** - According to **WHO guidelines for water, sanitation, and hygiene in schools**, the recommended minimum number of toilet facilities (urinals and latrines combined) is **1 per 60 students** for girls and **1 per 100 students** for boys. - These guidelines aim to ensure adequate access to sanitation facilities, reducing the spread of diseases and promoting a healthy learning environment. *40,100* - This option deviates from the WHO recommendations for girls, which suggest a **higher ratio of facilities** per student, specifically 1 per 60, not 1 per 40. - While the boys' ratio (1 per 100) is correct, the overall combination does not align with the most widely accepted guidelines. *60,90* - This option correctly states the ratio for girls (1 per 60) but incorrectly suggests 1 per 90 students for boys, whereas the WHO guideline is **1 per 100 students**. - Providing fewer facilities than recommended for boys could lead to overcrowding and hygiene issues. *40,90* - Both ratios in this option are incorrect according to WHO guidelines; the recommended number is **1 per 60 for girls** and **1 per 100 for boys**. - This combination would lead to insufficient facilities for both genders, potentially compromising health and sanitation standards.

Q: The majority of the waste produced by healthcare providers is

General waste. ***General waste*** - **General waste** (also known as municipal waste) constitutes the largest proportion of waste generated by healthcare facilities, including items like packaging, paper, food scraps, and office waste. - This type of waste is **non-infectious** and does not pose a specific biological or chemical hazard, making it similar to typical household or commercial waste. *Hazardous waste* - **Hazardous waste** accounts for a small percentage of total healthcare waste and includes chemical waste, pharmaceutical waste, and radioactive waste. - These categories require special handling and disposal due to their **toxic, corrosive, flammable, or reactive properties**, but they do not make up the majority of waste. *Biohazardous waste* - **Biohazardous waste** (or infectious waste) includes items contaminated with blood, body fluids, or infectious materials, but it represents a relatively small fraction (typically 10-15%) of the total waste generated. - While critical for proper management due to its **potential for disease transmission**, it is not the largest volume of waste. *Needle waste* - **Needle waste** (sharps waste) is a specific type of biohazardous waste composed of discarded needles, syringes, scalpels, and other sharp instruments. - Although it poses a significant **puncture injury hazard** and infection risk, its overall volume is very small compared to the total waste generated by a healthcare provider.

Q: Which of the following waste management methods is beneficial for soil building but may pose safety concerns if not properly managed?

Composting. ***Composting*** - Composting involves the **decomposition of organic waste** into a nutrient-rich material that significantly improves soil structure, fertility, and water retention. - However, if not managed properly (e.g., inadequate temperature, aeration, or presence of contaminants), it can lead to **odor problems**, attract pests, and potentially harbor pathogens, posing safety and health concerns. *Incineration of organic waste* - **Incineration** involves burning waste at high temperatures, which reduces its volume and can generate energy, but does not provide material for **soil building**. - This method can also release **pollutants and greenhouse gases** into the atmosphere and leaves behind ash that requires disposal. *Landfilling with controlled tipping* - Landfilling involves burying waste, which is a disposal method that serves to contain waste rather than **enrich soil**. - While controlled tipping aims to minimize environmental impact, it still poses risks of **leachate contamination** of groundwater and methane gas emissions. *No safe disposal methods available* - This statement is incorrect as there are multiple waste management methods that, when properly implemented, can be considered safe and beneficial. - Various techniques like recycling, composting, and proper landfill management are designed to minimize harm and maximize resource recovery.

Q: What is the maximum permissible chloride level in drinking water?

250 mg/L. ***250 mg/L*** - The **maximum permissible level** for chloride in drinking water, as per standards like those from the World Health Organization (WHO) and other regulatory bodies, is 250 mg/L. - Exceeding this level can lead to a **detectable salty taste** and contribute to the corrosion of metallic pipes and water heaters. *200 mg/L* - While this level is within acceptable limits, it is **not the maximum permissible level** defined by major health and environmental agencies. - Water with this chloride concentration would generally have **no noticeable taste or odor issues** related to chloride. *300 mg/L* - This level **exceeds the recommended maximum permissible limit** for chloride in drinking water. - At 300 mg/L, the water would likely have a distinctly **salty taste**, making it less palatable for consumption. *400 mg/L* - This concentration is significantly **above the safe and aesthetic limits** for drinking water. - Water with 400 mg/L chloride would be considered **unacceptable** due to its pronounced salty taste and potential for increased corrosivity.

Q: Which of the following statements about bleaching powder is false?

It is a stable compound. ***It is a stable compound*** - Bleaching powder, or **calcium oxychloride (CaOCl2),** is known to decompose over time, especially when exposed to air, light, or moisture, releasing chlorine gas and losing its effectiveness. - This decomposition indicates that it is **not a stable compound**; its chemical structure is prone to degradation under normal storage conditions. *Contains about 33% of available chlorine* - Bleaching powder's effectiveness is often quantified by its **"available chlorine"** content, which typically ranges from **25% to 35%**, making 33% a reasonable approximate value for commercial products. - This percentage represents the amount of chlorine that can be liberated to act as a **bleaching or disinfecting agent**. *White amorphous compound* - Bleaching powder is typically observed as a **white or yellowish-white powder**, lacking a definite crystalline structure, hence described as **amorphous**. - Its powdery appearance is consistent with its chemical composition and manufacturing process. *Strong bleaching agent* - The primary use of bleaching powder is as a **strong bleaching agent** due to the liberation of hypochlorite ions (OCl-) in solution, which are powerful oxidizers. - It is effective in **disinfecting water**, sanitation, and **bleaching textiles** due to its potent oxidative properties.

Q: Following latrines are suitable for camps and temporary use, except:

Septic tank. ***Septic tank*** - **Septic tanks** are large, underground chambers used for wastewater treatment over long periods, requiring significant installation and maintenance. - Their complexity and permanence make them **unsuitable for temporary camps** where quick setup and dismantling are essential. *Shallow trench latrine* - **Shallow trench latrines** are simple and quick to construct, making them ideal for short-term use in camps. - They involve digging a narrow trench, which can be easily covered and moved as needed, making them **temporary and effective**. *Borehole latrine* - **Borehole latrines** are relatively easy to construct in suitable soil conditions, often using an auger or boring tool to create a deep, narrow pit. - Their design allows for a good capacity for waste disposal in a **compact and temporary manner**, making them suitable for camps. *Pit latrine* - **Pit latrines** are a common and effective temporary solution, involving a dug pit covered by a squatting plate or seat. - They are simple to construct, low-cost, and **suitable for temporary settlements**, as they can be abandoned and covered when full.

Question 1

What is the reagent used in Horrock's apparatus for determining the chlorine demand of water?

Accepted Answer

Orthotoluidine

Answer

Methylene blue

Answer

Sodium bicarbonate

Answer

Starch iodide indicator

Question 2

The minimum recommended concentration of free chlorine in drinking water at the end of one hour (mg/L) is:

Accepted Answer

0.5

Answer

0.1

Answer

1

Answer

1.5

Question 3

According to WHO guidelines for water, sanitation and hygiene in schools, what is the recommended minimum number of toilet facilities (urinals and latrines combined) per students in a school setting?

Accepted Answer

60,100

Answer

40,100

Answer

60,90

Answer

40,90

Question 4

The majority of the waste produced by healthcare providers is

Accepted Answer

General waste

Answer

Hazardous waste

Answer

Biohazardous waste

Answer

Needle waste

Question 5

All of the following statements about purification of water are true except:

Accepted Answer

Presence of Clostridial spores indicates recent contamination of water

Answer

Sodium thiosulphate is used to neutralize residual chlorine in water samples

Answer

Coliforms must not be detectable in any 100 ml sample of drinking water

Answer

Coliforms may be detected by multiple tube method and indole production

Question 6

Which of the following waste management methods is beneficial for soil building but may pose safety concerns if not properly managed?

Accepted Answer

Composting

Answer

Incineration of organic waste

Answer

Landfilling with controlled tipping

Answer

No safe disposal methods available

Question 7

What is the maximum permissible chloride level in drinking water?

Accepted Answer

250 mg/L

Answer

200 mg/L

Answer

300 mg/L

Answer

400 mg/L

Question 8

Which of the following statements about bleaching powder is false?

Accepted Answer

It is a stable compound

Answer

White amorphous compound

Answer

Strong bleaching agent

Answer

Contains about 33% of available chlorine

Question 9

Which of the following statements regarding chlorination is most likely false under all circumstances?

Accepted Answer

Residual chlorine must always be 0.5 mg/L

Answer

Water should not be turbid

Answer

Chlorine demand should be estimated

Answer

Contact period - 30 minute

Question 10

Following latrines are suitable for camps and temporary use, except:

Accepted Answer

Septic tank

Answer

Borehole latrine

Answer

Pit latrine

Answer

Shallow trench latrine

Environmental Health — MCQs

Environmental Health — MCQs

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