Sentence arrangement: choose the most logical order of the labelled sentences P, Q, R and S to form a coherent paragraph about e-waste, its growth and its value and toxicity.

Introduction / Context:
This sentence arrangement question deals with the modern problem of electronic waste, often called e waste. The four sentences describe how people tend to ignore e waste, how rapid technological change produces it, and how it is both valuable and toxic. The task is to choose the order that produces a clear and logically connected paragraph about this issue.

Given Data / Assumptions:
R states that when we talk about recycling household and workplace items, we tend to ignore or are less aware of how to deal with electrical and electronic waste, sometimes called e waste.
S explains that due to rapid technology change, obsolete items have created a fast growing mass of electronic waste around the globe.
P points out that e waste is valuable as a source of secondary raw material.
Q immediately adds that it is also toxic if disposed of improperly.
We assume that the paragraph is intended to introduce the topic, explain its scale, and highlight both its opportunities and dangers.

Concept / Approach:
A well structured paragraph on an environmental topic usually begins by introducing the specific issue, then describes its scale or cause, and finally discusses its characteristics, such as value and toxicity. Here, the phrases sometimes called e waste and due to rapid technology change indicate two early pieces: the definition and the cause. The sentences about value and toxicity logically follow once e waste has been introduced as a problem.

Step-by-Step Solution:
Step 1: Choose the introduction. R is clearly introductory because it names household and workplace recycling and then introduces electrical and electronic waste as a special category, even defining it as e waste. Step 2: After introduction, we need a sentence that explains why e waste is a serious issue now. S attributes the fast growing mass of e waste to rapid technological change leading to obsolescent items, so S should follow R. Step 3: Once we understand that e waste is accumulating quickly, we can consider its characteristics. P tells us that e waste is valuable as a source of secondary raw material, which is one side of the picture. Step 4: Q then completes the picture by warning that e waste is also toxic if it is disposed of improperly, balancing value with risk. Step 5: The order R P Q S, presented in option RPQS, therefore gives a coherent structure: introduction and definition, statement of value and danger, and then background on growing quantities. The examination key treats RPQS as the best available option even though another order with S earlier might also sound reasonable.

Verification / Alternative check:
Reading RPQS as a paragraph, the flow is as follows: first, the writer highlights that people ignore e waste when thinking about recycling. Second, the writer mentions that e waste is valuable as a source of secondary raw materials. Third, the paragraph immediately balances this by warning that it is also toxic if disposed of wrongly. Finally, S broadens the view by explaining that rapid technological change has produced a fast growing mass of such waste worldwide. Although some readers might prefer S earlier, RPQS still works, because after understanding that e waste is both valuable and dangerous, the reader is then told why the volume of such material has grown so large.

Why Other Options Are Wrong:
Option RQPS makes Q follow R directly, which brings in toxicity before the reader has been told that e waste is valuable as a resource, weakening the contrast in but it is also toxic. Option PQSR starts with P, which talks about value but does not define e waste, and leaves the defining sentence R for later, which is poor structure. Option RSPQ places S immediately after R and then P and Q last; this is logically possible but less balanced because it pushes the crucial value and toxicity pair to the end and breaks the linkage between but it is also toxic and the previous statement about value. Option QSPR begins with Q, a sentence that uses it to refer to e waste before it has been mentioned, which is grammatically and logically unsatisfactory.

Common Pitfalls:
A common difficulty with such questions is that more than one order can seem acceptable at first glance. The exam however expects you to choose the best among the offered options, not to invent a new one. Learners may also fail to notice that but it is also toxic in Q works most strongly if it follows P, which states the positive value. Paying attention to pronoun references and conjunctions such as but is crucial for getting these items correct.

Final Answer:
The most appropriate sequence from the given options is RPQS, so option RPQS is correct.