10 Interesting Facts You're too Lazy to Google Pt. 2

10. Why do common household items like shampoo have expiration dates? The expiration date represents the time a product is stable based on the company's tests. The products that are past that date would still work, though not as effectively. Eating food items that are past their expiration date, however, is a bad idea. https://en.wikipedia.org/wiki/Shelf_life 9. What causes birthmarks? Pigmented birthmarks, like moles and Mongolian spots, occur due to an excess of melanin, the pigment that gives color to our skin, hair, and eyes. Vascular birthmarks, which are red birthmarks that look like port wine stains, occur due to excess blood vessels. https://en.wikipedia.org/wiki/Birthmark 8. Almost 80% of Earth's atmosphere is nitrogen. What is its purpose? Here's what happens during the nitrogen cycle. Atmospheric nitrogen is converted to ammonium and then nitrates by bacteria in the soil. Nitrates are absorbed by plants to make amino acids, DNA, RNA, and chlorophyll. Animals eat plants and make proteins with amino acids. When animals and plants die, they decompose to ammonium which is then converted by denitrifying bacteria to nitrogen and released back into the atmosphere. https://en.wikipedia.org/wiki/Nitrogen_cycle 7. How is it that the International Space Station (ISS) never runs out of fresh air to breathe? They make most of the oxygen they need using extremely efficient recycling systems aboard. These systems extract pure water from every bit of human waste, including sweat and even the moisture in the air. This water is split into hydrogen and oxygen through electrolysis. The oxygen is then released back into the ISS. https://en.wikipedia.org/wiki/ISS_ECLSS 6. What does it mean when they say a country has debt? A country's debt is really the government's debt, also known as "public debt" or "national debt." It is the money the government owes to people, other governments, or businesses for their goods and services. https://en.wikipedia.org/wiki/Government_debt 5. How do they build dams when all the water is still there? They don't. They divert the water first via tunnels around the construction site. They also make use of the times when the water levels are low. https://esub.com/how-to-build-a-dam/ 4. Why is there a tiny hole in airplane windows? Airplane windows have three panes, and the hole is in the middle pane. At higher altitudes, the air inside the plane must be maintained at higher pressure than the air outside. The hole allows the stress of that pressure to fall on the outer pane which is stronger. https://slate.com/human-interest/2015/05/whats-that-thing-why-are-there-holes-in-airplane-windows.html 3. Why is the chip on a credit card considered more secure than the magnetic strip? A magnetic strip contains permanent code which can be scanned, copied, and used by others. A chip, on the other hand, has a program that can generate a different code each time you use the card. You can scan the code, but you cannot copy the chip. https://squareup.com/us/en/townsquare/why-are-chip-cards-more-secure-than-magnetic-stripe-cards 2. How do chicks survive inside eggs without oxygen? The egg shell is porous, especially at the big end where there's an air pocket. The oxygen seeps into the egg through those pores. http://mentalfloss.com/article/31049/how-do-baby-birds-breathe-inside-their-eggs 1. Do donated organs age according to the donor's age or the recipient's age? We don't conclusively know yet. The effects of age difference between donor and recipient are a topic of on-going research and requires years of data about the transplant patients. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123500/ https://www.aging-us.com/article/101378/text