Free IELTS Academic Reading Practice Test 9 & Answers

Cartography, the science and art of mapmaking, is as old as human civilization itself. Long before the invention of written language, early humans carved crude spatial representations of hunting grounds and water sources into bone and stone. The earliest surviving map of the world, the Babylonian Imago Mundi, dates back to the 6th century BCE. Carved into a clay tablet, it depicts Babylon at the center of a flat, circular world surrounded by a “bitter river,” illustrating how early maps were often more ideological and religious than geographically accurate.

A major mathematical leap occurred in ancient Greece. In the 2nd century CE, the Greco-Roman scholar Ptolemy compiled the Geographia, a massive atlas that introduced the concept of a global grid system. Ptolemy assigned coordinates of latitude and longitude to thousands of locations across the known world, allowing maps to be reproduced accurately by anyone who understood the mathematical rules. Although his calculation of the Earth’s circumference was significantly too small, his coordinate system formed the basis of mapmaking for the next thousand years.

During the 16th-century Age of Discovery, global navigation necessitated a new kind of map. In 1569, Gerardus Mercator introduced the Mercator projection. Navigating the oceans using a globe was highly impractical for sailors, so Mercator designed a cylindrical projection that translated the spherical Earth onto a flat, rectangular piece of paper. The genius of the Mercator projection was that it preserved straight lines of constant compass bearing, making maritime navigation vastly easier. However, the trade-off was massive spatial distortion at the poles; on a Mercator map, Greenland appears to be the same size as Africa, even though Africa is actually 14 times larger.

Today, cartography has transitioned from paper to pixels. Geographic Information Systems (GIS) and satellite imagery have rendered traditional mapmaking almost obsolete. Modern digital maps do not just display physical topography; they are layered with immense amounts of dynamic data, including real-time traffic updates, demographic shifts, and climate modeling. The GPS systems in our smartphones constantly communicate with a network of satellites, positioning us on the globe with an accuracy of just a few meters, a feat that would have seemed like magic to early cartographers.

A. Almost everyone has experienced it: you hear a catchy song on the radio during your morning commute, and for the rest of the day, a short snippet of that melody replays in your mind on an endless loop. In cognitive psychology, this phenomenon is formally known as Involuntary Musical Imagery (INMI), though it is much more commonly referred to as an “earworm.” Research indicates that over 90% of the population experiences earworms at least once a week, making it one of the most common forms of spontaneous cognition.

B. So, why do our brains latch onto certain songs? Neuroimaging studies have shown that listening to music heavily engages the auditory cortex, the part of the brain responsible for processing sound. When a song stops playing abruptly, or when the brain is left with cognitive “downtime” (such as during a boring task like washing dishes), the auditory cortex essentially attempts to fill in the missing information. It begins to repeatedly fire the neural pathways associated with the song, creating a continuous mental loop.

C. Not all songs are equally likely to become earworms. Music psychologists have identified several key characteristics that make a tune particularly “sticky.” First, earworms tend to have an upbeat, fast tempo. Second, they usually feature a generic melodic contour, meaning the pitch rises and falls in a simple, predictable pattern—think of the classic nursery rhyme “Twinkle, Twinkle, Little Star.” Finally, sticky songs often contain unusual or repetitive intervals that make them stand out just enough to capture the brain’s attention without being too complex to remember.

D. While usually harmless, severe earworms can become a source of irritation and distraction. Consequently, researchers have studied various methods for banishing them. One effective technique is the “cognitive overload” method. Because the auditory working memory has a limited capacity, engaging in a task that requires intense focus, such as solving a difficult anagram or reading a complex text, forces the brain to allocate resources away from the auditory cortex, thereby breaking the musical loop.

E. Another, more surprising cure was discovered by researchers at the University of Reading: chewing gum. Because the physical act of chewing involves the same articulatory motor planning used to sing or speak, chewing gum interferes with the brain’s ability to mentally “vocalize” the earworm. By simply chewing a piece of gum, individuals can significantly reduce the frequency and intensity of the intrusive melody.

In 2004, two physicists at the University of Manchester, Andre Geim and Konstantin Novoselov, were conducting a playful Friday night experiment. Using a block of graphite (the same material found in standard pencils) and ordinary Scotch tape, they repeatedly peeled away layers of the graphite until they were left with a flake just one atom thick. This astonishingly simple experiment led to the isolation of graphene, a groundbreaking two-dimensional material that earned the pair the Nobel Prize in Physics in 2010.

Graphene is essentially a single layer of carbon atoms arranged in a hexagonal, honeycomb-like lattice. Despite its two-dimensional nature, its physical properties are nothing short of miraculous. Graphene is roughly 200 times stronger than structural steel, yet it is incredibly flexible and completely transparent. Furthermore, it is the most conductive material ever discovered at room temperature, allowing electricity and heat to pass through it with virtually zero resistance. These properties have led scientists to hail graphene as a “miracle material” capable of revolutionizing multiple industries.

One of the most highly anticipated applications for graphene is in energy storage. Modern lithium-ion batteries, used in everything from smartphones to electric cars, take hours to charge and degrade over time. By incorporating graphene into battery cells, engineers can create “supercapacitors” that charge in a matter of seconds and hold significantly more energy. Additionally, because graphene is a highly effective filter at the atomic level, it holds massive potential for desalination. Graphene membranes could theoretically filter the salt out of seawater at a fraction of the energy cost required by modern reverse osmosis plants, potentially solving the global water crisis.

However, realizing the promise of graphene has proven immensely difficult. The primary obstacle is manufacturing. While isolating a tiny microscopic flake of graphene using sticky tape is easy, producing large, flawless sheets of the material on an industrial scale is incredibly complex and expensive. The current chemical vapor deposition (CVD) methods used to synthesize larger sheets often result in structural defects in the carbon lattice. Even a single missing atom can drastically reduce the material’s strength and conductivity. Until engineers can find a cost-effective way to mass-produce perfect graphene, its revolutionary applications will remain largely confined to the laboratory.