Identify the correct statement from the options provided ?
Show answer Hide answer
Answer: D. All A., B. and C.
Explanation
Chemical oxygen demand measures oxidizable organic matter using potassium dichromate and correlates with biological oxygen demand. Each statement correctly describes a fundamental chemical characteristic of oxygen demand measurements in wastewater. Comprehensive water testing relies on combining multiple analytical parameters to evaluate pollution levels accurately. Chemical oxygen demand quantifies the total amount of oxygen required to oxidize organic compounds completely. Potassium dichromate acts as a strong chemical oxidizing agent in an acidic aqueous testing solution. Biological oxygen demand measures only the biodegradable fraction consumed by living microorganisms over five days.
Environmental agencies mandate chemical oxygen demand testing to monitor industrial effluent discharges into natural waterways. High chemical oxygen demand values indicate severe organic pollution that threatens aquatic ecosystem health significantly. Wastewater treatment plants track these oxygen parameters to optimize biological digestion processes before final discharge. Option A is correct individually, but it ignores the valid relationships described in the other statements. Option B correctly identifies the oxidizing reagent used, yet omits important details covered elsewhere. Option C accurately notes the empirical correlation with biological oxygen demand despite regional wastewater variations.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. What is the nutrient composition implied by a -10-5 fertilizer rating______________?
Show answer Hide answer
Answer: A. 5, 10, 5% respectively of N2, P2O5 and K2O
Fertilizer grades conventionally indicate the percentage composition of nitrogen, phosphate, and potash respectively. A standard numeric rating provides guaranteed analysis percentages for these three primary plant nutri...
Q2. How does the required number of stages respond when the reflux ratio in a continuous counter-current extraction setup is elevated_______________________?
Show answer Hide answer
Answer: B. Decrease
Increasing the reflux ratio returns more solvent back into the extraction column. This higher internal liquid traffic enriches the counter-current streams and improves separation efficiency. Consequently, fewer equilibri...
Q3. What is the reaction order depicted in the accompanying graphic, characterized by the rate expression -rA = KCA_________________?
Show answer Hide answer
Answer: D. 3
The rate expression convention and matching graphic coefficients determine reaction kinetics order. Complex chemical kinetics models evaluate the overall exponent sum in rate laws. Based on the provided rate expression p...
Q4. As ambient temperature climbs, the atomic heat capacities corresponding to all solid elemental substances_________________?
Show answer Hide answer
Answer: A. Increases
According to the Dulong-Petit law and general thermodynamic behavior, atomic heat capacities increase at high temperatures. Thermal agitation allows lattice atoms to vibrate with greater amplitudes, absorbing more therma...
Q5. How does the internal energy of a substance respond to an increase in temperature___________________?
Show answer Hide answer
Answer: A. Increases
Internal energy represents the total microscopic kinetic and potential energy stored within a given substance. Raising the temperature increases the average translational and rotational kinetic energy of its constituent...
Q6. What is the amount of work performed during the free expansion of a gas____________________?
Show answer Hide answer
Answer: B. Zero
Free expansion involves a gas rushing into an evacuated chamber against zero opposing external pressure. Mechanical work done is defined as the product of external pressure and the resulting volume change. Since external...