Facts about teeth, pupil (eye) and water expiry date

White teeth vs yellow teeth:

Yellow teeth are stronger than white teeth. Natural color of teeth is white. Whitening teeth weakens our teeth permanently.

Watching people we love

When we look at someone we love our pupil, a black hole located in the center of the iris of the eye that allows light to strike the retina, expands upto 45 percent.

Expiry date of water:

The expiry date written on water bottles is actually expiry date of plastic bottles not the water inside it. After this date chemicals from plastic start getting dissolved in water and changing its taste.