10 most difficult chemistry riddles A list of ten (out of 106) chemistry related questions that are the most often answered incorrectly Chemistry quiz Which of the following is true for the solution with the pH=0?The OH − ion concentration is smaller than the H+ ion concentration. In chemistry, pH is a numeric scale used to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm to base 10 of the activity of the hydrogen ion .Traditionally the pH is being defined as: pH = - log10 [H+], where [H+] it is a H+ ions concentration in mol/dm^3 (M). So if pH = 0 this H+ ions concentration is 1 mol/dm^3 and the solution is strongly acidic.very hard 24% the OH − ion concentration is smaller than the H+ ion concentrationthe OH − ion concentration is smaller than the H+ ion concentration24%the OH − ion concentration is greater than the H+ ion concentrationthe OH − ion concentration is greater than the H+ ion concentration19%the OH − ion concentration is equal of the H+ ion concentrationthe OH − ion concentration is equal of the H+ ion concentration28%Such solution doesn't existSuch solution doesn't exist27%Created by: Paweł Kołodziejczyk. Statistics based on 1714 answers in 2 languages »numbers riddles » Which has more calories: table sugar or aspartame?Pretty much the same. Aspartame produces 4000 kilocalories of energy per gram when metabolized, sucrose (table sugar) produces 3900 kilocalories, so the amount of energy produced by both is very similar. However, aspartame is approximately 200 times sweeter than sucrose, so it is consumed in much smaller doses. very hard 24% pretty much the samepretty much the same24%table sugar has much more caloriestable sugar has much more calories39%aspartam has much more caloriesaspartam has much more calories16%aspartam has no calories at allaspartam has no calories at all18%Created by: globalquiz.org. Statistics based on 1340 answers in 4 languages »food riddles » What is exactly the pH value of distilled water?It depends on the temperature. Pure water is about 7 at 25 °C; this value decreases with increasing temperatures. At 50 °C, it is 6.55. It is also worth to note, that water that has been exposed to air is mildly acidic, because it absorbs carbon dioxide from the air.very hard 26% 1.01.018%7.07.049%10.010.05%It depends on the temperatureIt depends on the temperature26%Created by: globalquiz.org. Statistics based on 3361 answers in 4 languages »acids riddles » 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 31% carboncarbon27%oxygenoxygen19%ironiron31%siliconsilicon20%Created by: globalquiz.org. Statistics based on 5695 answers in 2 languages »Earth riddles » Methanol (wood alcohol) is highly poisonous. Comparing to ethanol, is it more or less sedative?Less sedative. Methanol has a much weaker sedative effect than ethanol, which leads the victim to drink more than it would normally do with ethanol. Methanol is oxidized to formaldehyde and then to the poisonous formic acid in the liver. very hard 31% more sedativemore sedative37%the samethe same20%less sedativeless sedative31%that depends on the temperaturethat depends on the temperature10%Created by: MarcusX. Statistics based on 5468 answers in 2 languages »alcohol riddles » Why is White Sands Desert in New Mexico so purely white?It is gypsum. White Sands, having 442 total square kilometers of dune fields, is the world's largest surface deposit of gypsum. Unlike other desert sands, it is cool to the touch, due to the high rate of evaporation of surface moisture and the fact that the sands reflect, rather than absorb, the sun's rays.very hard 31% it is gypsumit is gypsum31%it is very fine grained sandit is very fine grained sand10%it iswhite quartzit iswhite quartz35%it is an optical illusionit is an optical illusion22%Created by: Debbie Fox. Statistics based on 10030 answers in 4 languages »soil riddles » This is an iron buoy. Where were its atoms formed?In a high-mass star preceding Sun. Radioactive nickel-56 (which decays to the most common isotope of iron) is the last element to be produced before the collapse of a supernova. That is why the iron was abundantly scattered into space after the supernova explosion.very hard 34% in a high-mass star preceding Sunin a high-mass star preceding Sun34%in the Sunin the Sun8%in the Earth's corein the Earth's core29%in the Earth's crustin the Earth's crust26%Created by: life-o-holic. Statistics based on 9106 answers in 2 languages »elements riddles » Who invented the mercury-in-glass thermometer?Gabriel Daniel Fahrenheit. Daniel Gabriel Fahrenheit was a German physicist, engineer, and glass blower who is best known for inventing the mercury-in-glass thermometer (1714), and for developing a temperature scale now named after him very hard 34% Galileo GalileiGalileo Galilei22%Anders CelsiusAnders Celsius29%Gabriel Daniel FahrenheitGabriel Daniel Fahrenheit34%William KelvinWilliam Kelvin13%Created by: Paweł Kołodziejczyk. Statistics based on 2327 answers in 4 languages »inventors riddles » How are white pigments used in paints called?Lithopone, a mixture of barium sulfate and zinc sulfide, is widely used as a white pigment powder for paints, putties and plastics. Approximately 220,000 tons of lithopone were produced in 1990. very hard 34% LimeLime29%FlavonesFlavones19%LithoponeLithopone34%OchreOchre16%Created by: Paweł Kołodziejczyk. Statistics based on 1930 answers in 2 languages »colors riddles » What was included in the original Pepsi-Cola recipe?Digestive enzyme. Pepsi Cola, first introduced in 1898, was named after pepsin (enzyme) and kola (nuts). In 1931, the company entered bankruptcy and changed hands. The new owners changed the recipe to resemble more Coca-Cola.very hard 35% coke from coalcoke from coal6%saltpetersaltpeter16%digestive enzymedigestive enzyme35%heroinheroin40%Created by: Kasia. Statistics based on 11006 answers in 4 languages »beverages riddles » Play chemistry quiz and see all the questions.