The most difficult Earth riddles A list of Earth related questions that are most often answered incorrectly Geology quiz What is the most common element (by mass) forming the planet Earth?Iron is most abundant in the Earth's outer and inner core, and it is the fourth most common element in the Earth's crust.very hard 29% carboncarbon28%oxygenoxygen20%ironiron29%siliconsilicon20%Created by: globalquiz.org. Statistics based on 8380 answers in 2 languages »elements riddles » In which month is the Earth closest to the Sun?In January. Earth's perihelion occurs around January 3, and the aphelion around July 4. The distance change is about 3.5%, which gives 6.9% increase in solar energy reaching the Earth at perihelion relative to aphelion. Since the southern hemisphere is tilted toward the perihelion, the southern hemisphere receives more energy from the Sun than does the northern over the course of a year. hard 44% in Januaryin January44%in Marchin March6%in Junein June33%there is no differencethere is no difference15%Created by: globalquiz.org. Statistics based on 13353 answers in 4 languages »Sun riddles » If Earth's radius was larger by 1 meter, how much longer would its equator be?By approx 6 meters. For each circle, the length of the circumference is c=2πr. Hence, if a radius grows by 1 meter, the circumference grows by 2 π meters - no matter what the initial value of radius was.hard 45% by approx 6 metersby approx 6 meters45%by approx 6 kilometersby approx 6 kilometers18%by approx 60 kilometersby approx 60 kilometers21%by approx 6000 kilometersby approx 6000 kilometers15%Created by: SpikeMe. Statistics based on 25572 answers in 2 languages »math riddles » What object collided with Earth according to giant impact hypothesis?A planet. According to the giant impact hypothesis Earth once collided with a planet of Mars size usually referred to as Theia, a titaness of Greek mythology, mother of Selene - Moon goddess, which is to reflect the believe the collision was an origin of the Moon. hard 45% a cometa comet10%a moona moon8%an asteroid an asteroid 34%a planeta planet45%Created by: smyru. Statistics based on 6178 answers in 2 languages »universe riddles » After what is the Jurassic period named?A mountain range in Switzerland. The Jurassic period is named for the Jura Mountains in between France and Switzerland, where many fossils have been found.hard 47% a type of ancient lizarda type of ancient lizard12%a mountain range in Switzerlanda mountain range in Switzerland47%a type of coal formed in that perioda type of coal formed in that period15%Latin for 'before mammals'Latin for 'before mammals'24%Created by: MarcusX. Statistics based on 12237 answers in 2 languages »Switzerland riddles » What part of the Earth's surface is dry land?29,2%. It is currenlty 29.2% - but it may decrease in the near future due to global warming and sea level rise.hard 54% 29,2%29,2%54%33,6%33,6%28%38,4%38,4%11%42,1%42,1%5%Created by: Krzysztof Moskal. Statistics based on 6969 answers in 2 languages »water riddles » Why is the ozone hole dangerous?It increases UV radiation. In the ozone layer, ozone molecules absorb UV-B and UV-C radiation - short wavelength forms of ultraviolet that can disrupt organic molecules, producing cancerous changes in living cells.easy 70% it speeds up the global warmingit speeds up the global warming21%it increases UV radiationit increases UV radiation70%it depletes the oxygen (O2)it depletes the oxygen (O2)4%it disturbs Earth's magnetic fieldit disturbs Earth's magnetic field3%Created by: Riho Ishii. Statistics based on 10511 answers in 4 languages »ecology riddles » Play geology quiz and see all the questions.