Reading Passage 2
A
What inventions have changed the way we live for the better? If you set out to ask this question, most people will name the invention of the wheel or electricity. Younger respondents might come up with something recent, like the Internet. The more educated could remember the printing press. However, very few are likely to mention discovering the method of producing glass, despite its ubiquity and how long it has been around. So, is glass the underdog invention of human civilization?
B
Glass is an amorphous solid material that is transparent and brittle. It is composed of silica, sodium oxide, and calcium oxide. It is hard and has a high melting point. It is also a good insulator, meaning that it does not conduct electricity, and can be used to transmit light. Glass has a low coefficient of thermal expansion – in other words, it does not expand or contract much when exposed to heat or cold. It is also resistant to corrosion and does not react with many chemicals, making it perfect for outdoor applications, especially when it has to be exposed to the elements.
C
Glass has been around for millions of years, but it wasn’t until about 3500 BC, effectively predating iron smelting, that humanity managed to produce it artificially. The earliest known use of glass can be tracked down to Mesopotamia, in the form of beads and other decorative objects. Around 1500 BC, glassmakers in Lebanon began creating glass by heating sand and other ingredients in a furnace. This process, known as glass blowing, made it possible to give the molten glass a variety of shapes and sizes. This method was used to make windows and primitive lenses, as well as decorative objects. In the first century AD, artisans in Rome pioneered the method of mixing glass, sand, and other ingredients with lead oxide. Referred to as glass staining, this technique allowed to introduce colours and texture alteration of glass.
D
It is worth noting that glass is technically not a human invention as it occurs naturally in various forms. It is most commonly formed when certain types of rocks are heated to high temperatures and then cooled quickly. Such glass can be found in the form of obsidian – a black, glass-like rock, and tektites, which are small, glassy objects that are thought to have been created by meteorite impacts. Fulgurite is probably the first form of glass, colloquially referred to as natural glass, which is formed when lightning strikes a sandy beach or desert. The intense heat melts the sand and creates a glass-like material. To the uninitiated, however, it won’t look like glass at all, as it is usually impossible to see anything through it. The few natural examples of this material that do look man-made are usually not transparent, but translucent – you can see light coming through them, but it is difficult to make out the object on the other side. The latter is one of the hallmark qualities of “real” glass.
E
Glass has been used by humans for thousands of years, and its usage has only grown over time. From windows to drinking vessels, glass has become an integral part of our lives. Today, glass is needed in a variety of industries, ranging from construction to medicine. In construction, glass is found in windows, doors, and skylights. These allow natural light to enter a building, reducing the need for artificial lighting and thus saving energy. Glass is also indispensable in conservatories and greenhouses, which help regulate temperatures and ensure an optimal environment for plants. Automotive industry would probably not even exist without it – windshields and lights being only a few examples of how this material can be used there. Food and drink containers made of glass are said to better preserve the taste and aroma.
F
Glass is created through a process known as smelting, which involves heating sand, soda ash, and limestone at extremely high temperatures. One of the unwanted consequences of this is the infamous carbon dioxide, a greenhouse gas that gets released into the atmosphere. Additionally, the production requires a large amount of energy, which is often generated from burning fossil fuels, thereby indirectly contributing to further environmental damage. Glass production also requires the use of chemicals such as sulfuric acid that is harmful to the environment if not properly disposed of. Furthermore, the disposal of glass can be problematic. Glass is not biodegradable so it can take thousands of years to decompose, and it is not easily recycled. As a result, it often ends up in landfills, where it takes up valuable space, and while the material itself is chemically stable and therefore does not cause damage, the sheer amount of it still presents a problem.
G
Like most things, glass as a material has its limitations. It is not always the best choice due to its fragility, weight, and cost. Nowadays, there are materials that can serve as a substitute to glass, offering the same or better performance depending on the application. One of them is polycarbonate. It is a thermoplastic that is lightweight, strong, and shatter-resistant – it does not break into multiple small pieces if damaged. It is often used in place of glass for things like bulletproof windows, safety shields or eye protection. Another sphere of wide adoption is in the automotive industry, where its shatterproof qualities proved irreplaceable when making headlights, taillights, and windshields.
H
So, what does the future hold for glass? A lot of uncertainty is the only thing that can be said for sure! Even though glass itself is more eco-friendly than comparable materials such as plastics and its many derivatives, making, transporting and disposing of it entails higher financial and ecological overheads. This is the main reason why the glass bottle that ruled the supermarket shelves till late nineties is a rare sight nowadays, replaced by a more versatile, even if less charismatic plastic counterpart. And it’s just a taste of things to come.
Questions 14-21
Reading Passage 1 has eight paragraphs labelled A-I.
Choose the most suitable headings for paragraphs B-I from the list of headings below.
Write the appropriate numbers (I-XII) in boxes 14-20 on your answer sheet.
One of the headings has been done for you as an example.
Note: There are more headings than paragraphs, so you will not use all of them.
Example: Paragraph A — Answer III
List of Headings
I Glass in nature
II Bottles to be banned
III Underappreciated
IV How to use glass
V Taking a closer look
VI Dim prospects
VIII Through the looking glass of time
IX Taking a toll on nature
X A thousand applications
XI Not without a fault
XII Irreplaceable – or is it?
14 Paragraph B
15 Paragraph C
16 Paragraph D
17 Paragraph E
18 Paragraph F
19 Paragraph G
20 Paragraph H
Questions 21-24
In boxes 21-24 on your answer sheet, write
YES if the statement agrees with the claims of the writer
NO if the statement contradicts the claims of the writer
NOT GIVEN if it is impossible to say what the writer thinks about this
21 Glass is not the first thing that comes to mind as a groundbreaking invention
22 As a material, glass became popular owing to its practicality when used outside
23 Iron smelting was invented before production of glass was possible
24 Introducing additives to the mixture enabled glass to have various desirable properties
Questions 25-28
25 Glass that occurs naturally
A Shares few desirable properties with artificial glass
B Can mostly be found in desert landscapes
C Is prized for its unique properties
26 The main ecological concern when it comes to glass is that
A Its production creates an undesirable by-product
B Glass fragments contain sulfuric acid
C Burying it underground requires special safety measures
27 Polycarbonate is chosen over traditional glass primarily because
A It is cheaper to make
B It provides certain safety benefits
C It is eco-friendly
28 What does the author imply in the closing sentence of the text?
A The taste of liquids held in bottles is likely to be affected by plastic
B Bottles are likely to find new application in the future
C The replacement trend is likely to continue
For this task: Answer keys :: Vocabulary