Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-99

Have you ever wondered how a simple bar of soap is made? While it seems like a basic everyday object, its creation is a fascinating chemical journey. The manufacturing of soap follows a precise and traditional method that has been refined over centuries. The (21) __________ chemical reaction involved is called saponification, which is essentially the process of turning fats and oils into soap. This transformation is the core of all soap production.

The process begins with the careful selection of ingredients. First, fats or oils, which can come from either vegetable or animal sources, (22) __________ with an alkali. A common alkali used in soap making is sodium hydroxide, also known as lye. This mixture is then heated to a specific temperature and stirred continuously. Heating helps to accelerate the saponification reaction, ensuring that all the oil and lye react completely.

Then, once the reaction is complete, the mixture thickens into a hot, liquid soap. At this stage, other ingredients like fragrances, colors, or essential oils can be added to customize the final product. The liquid soap is then carefully poured into large trays called molds. It is left in these molds to cool and begin the hardening process, which is a critical step for creating a solid bar.

After being poured, the soap must be left to 'cure' for several weeks. This waiting period is (23) __________ because it allows the saponification to finish and the soap to harden fully. It also lets any excess water evaporate, resulting in a harder, longer-lasting bar. (24) __________ bar of soap must go through this curing stage; skipping it would result in a soft and unusable product. The patience required here is key to quality.

Finally, after the curing is complete, the large blocks of soap are removed from their molds. They are cut into the familiar smaller bars which we buy in stores. These bars are often stamped with the manufacturer's logo and then inspected for quality before being packaged. The entire process, from mixing raw ingredients to the finished bar, takes both scientific precision and careful craftsmanship.

Globally, the urgent push towards electric vehicles (EVs) aims to combat urban air pollution and reduce carbon emissions from transportation. [I] This worldwide shift sees governments and industries investing heavily in greener alternatives. [II] The familiar roar of gasoline engines is slowly yielding to the quiet hum of electric counterparts, prompting a crucial question: are electric motorbikes truly the clean future for Vietnam's iconic, crowded streets? [III]

The primary appeal of electric motorbikes lies in their environmental benefits. Unlike gasoline bikes, e-motorbikes produce zero tailpipe emissions, directly improving urban air quality by reducing harmful pollutants. This can significantly benefit public health. [IV] They also promise reduced greenhouse gas emissions, especially if charged with renewable energy. Vietnamese companies like Vingroup, via VinFast, have heavily invested in producing their own electric motorbikes, making EVs a highly visible topic nationwide, championing this cleaner vision.

For many young people in Vietnam, particularly 14-15 year olds, electric motorbikes are becoming an increasingly popular and practical choice. Their ease of use, lower operating costs (due to cheaper electricity), and sleek designs make them attractive for daily commutes. They are quieter, smoother to ride, and often require less maintenance. This immediate appeal of convenience and modernity makes them a common sight among students, offering a tangible experience of "green technology" in their daily lives.

However, the path to a truly "green" future with electric motorbikes is not without complexities. While tailpipe emissions are zero, manufacturing their batteries, often containing rare earth minerals, carries significant environmental costs, from resource depletion and pollution in production to the challenge of disposal and recycling. Furthermore, an electric motorbike's "cleanliness" depends on how its electricity is generated. If the power grid relies heavily on fossil fuels, emissions simply shift from the street to the power plant, diminishing the overall environmental benefit.

So, are electric motorbikes the definitive clean future for Vietnam? They certainly offer compelling advantages in reducing urban air pollution and noise, directly benefiting public health. Their growing popularity, especially among younger generations, signals a positive shift. Yet, achieving true sustainability requires a holistic approach, addressing battery lifecycle concerns and ensuring a transition to cleaner energy for charging. Ultimately, electric motorbikes represent a vital step towards a greener Vietnam, but their full potential hinges on continued innovation and responsible development considering their entire environmental footprint.