Correct: C. Africa

The Sahara Desert is located on the continent of Africa and is the largest hot desert in the world. It covers roughly 9.2 million square kilometers (3.6 million square miles), which is about the same size as the entire United States or China. It spans nearly the entire width of North Africa, from the Atlantic Ocean to the Red Sea. The Sahara is famous for its massive sand dunes (ergs), which can reach heights of 180 meters (nearly 600 feet).

Correct: B. Gobi

The Antarctic Desert is the coldest and largest desert in the world, covering the entire continent of Antarctica with an area of about 14 million square kilometers. While we often think of deserts as hot and sandy, a desert is scientifically defined by low precipitation; because Antarctica receives less than 200 mm of rain/snow per year, it fits the definition perfectly.

Correct: C. Gobi

The Gobi Desert is the largest desert in Asia, stretching across parts of northern China and southern Mongolia. It is a "rain shadow" desert, created because the massive Himalayan mountain range blocks rain-carrying clouds from reaching the region, resulting in an arid landscape of rocky plateaus and sand dunes.

Correct: A. Arabian

The Rub' al Khali, or "Empty Quarter," is the largest continuous sand desert in the world, covering about a third of the southern Arabian Peninsula. It spans across Saudi Arabia, Oman, the United Arab Emirates, and Yemen, and it is known for its massive, towering sand dunes that can reach heights of up to 250 meters.

Correct: C. Antarctic

The Antarctic Desert is the largest desert in the world, covering over 14 million square kilometers of the Earth's southernmost continent. Although we often associate deserts with heat and sand, the scientific definition of a desert is any region that receives extremely low precipitation, and Antarctica is the driest place on the planet.

Correct: C. Atacama

The Atacama Desert in Chile is widely considered the driest non-polar place on Earth, with some weather stations there having never recorded a single drop of rain. It is a high-altitude plateau situated between the Andes Mountains and the Pacific Ocean, creating a "rain shadow" effect that blocks moisture. Because of its clear skies and lack of light pollution, it is home to some of the world's most powerful astronomical observatories.

Correct: B. Mojave

The Joshua Tree is a unique, tree-like succulent that is native only to the Mojave Desert in the Southwestern United States. It belongs to the Agave family and is characterized by its twisted branches and spiky, dagger-like leaves. These "trees" are an essential part of the desert ecosystem, providing food and shelter for many birds, mammals, and insects.

Correct: C. Chile

The Atacama Desert is a plateau in South America, primarily located in Chile, and is officially recognized as the driest non-polar place on Earth. Some parts of the desert have never recorded a single drop of rain in human history, and the landscape is so barren that it is often compared to the surface of Mars. Because of its high altitude and clear, dry air, it is one of the best locations in the world for astronomical observations.

Correct: D. Mongolia

The Gobi Desert is a large, cold desert region that covers parts of northern and northwestern China and southern Mongolia. It is a "rain shadow" desert, formed because the Himalayan mountain range blocks moisture-carrying clouds from reaching the area. Unlike the sandy Sahara, much of the Gobi is composed of bare rock and gravel, and it is known for its extreme temperature fluctuations.

Correct: A. California

The Mojave Desert is primarily located in the US state of California, although it also extends into parts of Nevada, Arizona, and Utah. It is the smallest and driest desert in North America and is famous for its unique Joshua trees and the extreme heat of Death Valley. This desert is a popular location for tourism, aerospace testing, and large-scale solar power projects due to its clear skies and intense sunlight.

Correct: A. India

The Thar Desert, also known as the Great Indian Desert, is primarily located in northwestern India, with a smaller portion extending into eastern Pakistan. It is one of the world's most densely populated desert regions and is characterized by shifting sand dunes and sparse vegetation. The desert forms a natural boundary between India and Pakistan and is a vital region for local nomadic communities and wildlife like the Blackbuck.

Correct: D. Antarctic

The Antarctic Desert is the largest desert in the world, covering the entire continent of Antarctica. While most people associate deserts with sand and heat, they are scientifically defined by their extremely low levels of precipitation. Antarctica receives so little snow or rain that it is classified as a cold desert.

Correct: A. Antarctic

The Antarctic Desert is the largest desert in the world, covering approximately 14.2 million square kilometers (5.5 million square miles). Despite being covered in ice, Antarctica meets the scientific definition of a desert because it receives extremely little precipitationaveraging only about 166 millimeters (6.5 inches) per year.

Correct: D. 0.7

Approximately 70% of Australia is arid or semi-arid - making it the world's driest inhabited continent after Antarctica. Australia contains 10 named deserts covering approximately 1.5 million square kilometres.

Correct: B. Great Victoria Desert

The Great Victoria Desert is Australia's largest desert - covering approximately 348,000 square kilometres in Western Australia and South Australia. Uluru (Ayers Rock) is located in the Northern Territory's Simpson/Tanami adjacent region in the Uluru-Kata Tjuta National Park.

Correct: D. Danakil Depression

The Danakil Depression in Ethiopia and Eritrea is one of Earth's most extreme environments - it includes the Afar Triangle (one of the hottest places on Earth year-round), volcanic lava lakes, acid pools, and salt flats forming at one of the lowest elevations on the African continent.

Correct: D. Kavir Desert

The Kavir Desert (Great Salt Desert, Dasht-e Kavir) is a large salt desert in north-central Iran - covering approximately 77,600 square kilometres. It consists of vast salt flats (kavir) formed by evaporating water in a closed basin.

Correct: A. Gobi Desert

The Gobi Desert has been expanding southward due to desertification - driven by overgrazing, drought, deforestation, and climate change. China's Great Green Wall initiative (Three North Shelter Forest Programme) has planted billions of trees to halt its advance.

Correct: B. Saltation (sand grains bounce along surface)

Saltation is the primary mode of sand transport in deserts - sand grains are lifted briefly by wind, travel in arcing paths before landing, and on impact kick up other grains. Approximately 75-80% of desert sand movement occurs through saltation.

Correct: D. Oman

The Wahiba Sands (Al Sharqiyah Sands) in Oman cover approximately 12,500 square kilometres of the Al Sharqiyah region - a spectacular sand sea with dunes reaching 100-200 metres. The desert is inhabited by Bani Wahiba Bedouin who maintain traditional camel herding practices.

Correct: B. Grand Erg Oriental

The Grand Erg Oriental (Great Eastern Erg) is one of the Sahara's largest sand seas - covering approximately 192,000 square kilometres in Algeria and Tunisia with dunes reaching 30 metres. It is one of the most extensive continuous sand deserts on Earth.

Correct: D. Artesian oasis

Artesian oases occur where water from an artesian aquifer (pressurised underground water) reaches the surface naturally through springs or seeps - the water comes from distant recharge areas where rainfall percolates into the ground and is under pressure from overlying rock.

Correct: D. Hammada

Hammada (also spelled hamada) refers to a high rocky desert plateau - essentially bare rock or thin gravel surfaces stripped of sand by the wind. Approximately 70% of the Sahara is hammada and reg (gravel plains) rather than sand dunes.

Correct: A. Nigerien Sahara

The Dabous Giraffes are ancient rock engravings in the Air Mountains region of Niger in the Sahara - the world's largest known rock engravings of giraffes, created approximately 6,000-9,000 years ago when the Sahara was greener and supported large wildlife including giraffes.

Correct: B. Baja California Desert

The Baja California Desert is the ecoregion covering most of Mexico's Baja California Peninsula - a distinct desert flora dominated by cardn cacti (the world's largest cacti), cirio (boojum tree), and other endemics.

Correct: C. Tassili n'Ajjer

Tassili n'Ajjer in southeastern Algeria is a UNESCO World Heritage Site containing over 15,000 prehistoric rock art engravings and paintings - one of the world's most important collections of prehistoric art documenting the Green Sahara period.

Correct: D. Karakum Desert

Merv is located in the Karakum Desert of present-day Turkmenistan - it was one of the great oasis cities of the Silk Road and at various times was one of the world's largest cities. The ruins (Mary UNESCO World Heritage Site) include layers from multiple historical periods.

Correct: A. Libya

Libya is approximately 90-95% desert - essentially the entire country except its narrow Mediterranean coastal strip is Saharan desert. Libya has some of the Sahara's most dramatic desert landscapes including the Fezzan region with its spectacular rock formations and ancient caravan routes.

Correct: B. Atacama Desert

The Nazca Lines are located in the Nazca Desert of Peru - a high plateau in the coastal desert region just inland from the Pacific coast. The geoglyphs were created by the Nazca culture approximately 500 BCE - 500 CE.

Correct: D. Yardangs

Yardangs are wind-sculpted landforms found in desert environments - created when wind carrying sand particles abrades and erodes soft rock into streamlined ridges orientated parallel to the prevailing wind. They can range from small features to enormous formations kilometres long.

Correct: C. Low albedo

Deserts have low albedo (low reflectivity) - dark sand, gravel, and rock surfaces absorb 75-90% of incoming solar radiation rather than reflecting it. This absorbed radiation heats the surface extremely rapidly, which then heats the air above it.

Correct: C. Foehn

The foehn (Fhn) effect produces warm dry winds on the lee side of mountains - as moist air rises over a range it cools and loses moisture through precipitation; on the descending side the now-dry air warms adiabatically at a faster rate (dry adiabatic lapse rate vs wet adiabatic lapse rate) creating a warm dry wind.

Correct: B. Great Sand Dunes

The Great Sand Dunes National Park in Colorado contains the tallest sand dunes in North America - reaching heights of 229 metres. They are located in the San Luis Valley surrounded by the Sangre de Cristo Mountains.