Which regions are mentioned as being affected by water scarcity due to natural and man-made disasters?

• Brazil and Argentina

• California and New York

• Haiti and West Africa

• Australia and Japan

What is the primary mechanism that solar stills use to purify water?

• Boiling and cooling

• Filtration through sand

• Chemical treatment

• Evaporation and condensation

What is the main advantage of using solar stills in areas without large-scale water purification systems?

• They need constant maintenance

• They are simple and use solar energy

• They require complex machinery

• They are powered by electricity

How pure is the water produced by a solar still?

• 50% pure

• 99.9% pure

• 100% pure

• 75% pure

What is the approximate cost of a well-designed solar still that can produce around 10 liters of clean water per day?

• $100

• $1000

• $2000

• $400