Which of the following is generally known as the largest hot desert in the world?

Introduction / Context:
Deserts are classified by extremely low rainfall, and they can be hot or cold. While Antarctica is technically the largest desert overall, general knowledge questions often refer to the largest hot desert. This question tests whether you can correctly identify the Sahara as the world's largest hot desert, a common point in school geography and competitive exams.

Given Data / Assumptions:

• The options are Sahara, Thar, Kalahari and “none.”
• The question uses everyday GK convention and focuses on hot deserts rather than all deserts including polar ones.
• We assume regions are being compared by area.

Concept / Approach:
Under strict scientific criteria, Antarctica and the Arctic are the largest deserts due to their extremely low precipitation. However, most exam questions about “largest desert” informally mean the largest hot desert. The Sahara Desert in North Africa covers around 9 million square kilometres, making it the largest hot desert. Thar and Kalahari are significant but much smaller in area.

Step-by-Step Solution:
Step 1: Recall that the Sahara, Thar and Kalahari are all hot deserts, but vary greatly in size. Step 2: The Sahara Desert stretches across many North African countries and is known to be the largest hot desert in the world. Step 3: The Thar Desert lies mainly in India and Pakistan and is much smaller than the Sahara. Step 4: The Kalahari Desert in southern Africa is also smaller than the Sahara in total area. Step 5: Thus, within the context of hot deserts, the Sahara is the correct answer.

Verification / Alternative check:
Geography textbooks often provide a table of major deserts, listing the Sahara as approximately 9 million square kilometres, while the Thar and Kalahari deserts are several hundred thousand square kilometres each. Polar regions are mentioned separately as cold deserts. This comparison confirms that, when speaking of hot deserts, the Sahara is the largest and is the expected answer in general knowledge examinations.

Why Other Options Are Wrong:
Thar: The Thar Desert, also called the Great Indian Desert, is relatively small compared to the Sahara and does not hold the world record in area.

Kalahari: The Kalahari is a large semi-arid region in southern Africa but is still much smaller than the Sahara.
None: This option is incorrect because there is a clear and widely accepted answer under the common GK convention, which is the Sahara Desert.

Common Pitfalls:
Some students may remember that Antarctica is technically the largest desert and mistakenly think that none of the options is correct. However, exam questions like this usually assume the commonly accepted GK interpretation that points to the largest hot desert. Others may be confused by regional importance of the Thar Desert in India and overestimate its size. Keeping the global scale in mind helps avoid these errors.

Final Answer:
Therefore, the largest hot desert commonly referred to in general knowledge is the Sahara.