Which common acid is found in citrus fruits like lemons and oranges giving them a sour taste?

Which scientific law explains that every object attracts every other object with a force proportional to their masses?

Which everyday device uses the principle of capillary action to function?

Which vitamin is produced when ultraviolet light acts on cholesterol in the skin?

Which type of chemical bond involves the sharing of electrons between atoms?

Which scientist is credited with developing the first successful smallpox vaccine?