Science quiz

More questions about Science

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   What mild animal infection prompted Edward Jenner to develop the first vaccine?

   Answer: Cowpox

   Why: The English word vaccine actually originates from 'vacca', the Latin word for cow.

2. 2 Medium

   How does solid ice manage to float on liquid water?

   Answer: Ice is less dense than water

   Why: Water is one of few liquids that expands upon freezing, preventing lakes from freezing solid from the bottom up.

3. 3 Hard

   What percentage of the universe consists of dark matter and energy?

   Answer: 95%

   Why: Planck satellite data puts dark energy near 68 percent and dark matter near 27 percent, leaving under 5 percent ordinary matter.

4. 4 Easy

   Which material is the hardest naturally occurring substance on Earth?

   Answer: Diamond

   Why: Simulations predicted lonsdaleite would be 58% harder than diamond, but a 2023 test on a meteorite sample found its hardness was only similar.

5. 5 Medium

   What effect lets hot water freeze faster than cold?

   Answer: Mpemba effect

   Why: Named after Tanzanian student Erasto Mpemba, the effect describes instances where warm water reaches freezing faster than colder water.

6. 6 Hard

   What color is deoxygenated human blood when flowing inside living veins?

   Answer: Dark red

   Why: Human blood is always red; veins appear blue on the surface because skin and subcutaneous fat scatter red wavelengths while reflecting blue light.