a$.$ Provide an overview of chlorine dioxide and its chemical properties, highlighting its role

as a disinfectant in water treatment and sanitation. $(10)$

b$.$ Identify and describe at least three alternative disinfectants commonly used in water

treatment processes. $(6)$

c$.$ Compare and contrast the effectiveness of chlorine dioxide with the identified alternative

disinfectants in terms of:

i$.$ Microbial inactivation spectrum and efficacy against pathogens. $(8)$

ii$.$ Residual disinfection capabilities and persistence in water systems. $(8)$

iii. Formation of disinfection by$-$products $($DBPs$)$ and potential health risks. $(8)$

iv$.$ Environmental impact, including factors such as toxicity, biodegradability, and

ecological implications. $(16)$

v$.$ Operational considerations, including ease of application, handling, and compatibility

with existing infrastructure.