6. Why is it that water freezes on the surface of a lake but not below it?
We all have observed that the surface of the pond or a lake freezes during winters, but the water underneath the surface remains in a liquid state.
The density of a substance plays an important role in how it interacts with its environment. Usually, everything that changes from liquid to a solid-state gets denser. Water, on the other hand, has an amazing property which makes it less dense when it is in a solid-state. The density of water increases when the temperature drops. At 4 °C, water reaches its maximum density and then decreases its density as its temperature goes down to the freezing point. This is because the solid state of water is crystalline in form which allows more space between the molecules than liquid water. Because of this, the less-dense ice does not sink in a glass of water. When the temperature of the surroundings start reaching the freezing point, the water molecules on the surface of the lake which are in direct contact with cold air start to freeze and instead of sinking, float on top of the water due to their low density. (source)
7. Why do people snore?
The reason people snore is that while asleep, their muscles relax which obstructs the flow of air causing the air to vibrate and create the snoring sound. When a person is asleep, the muscles in their body relax, including the ones that support the air passage. Due to this obstruction, the air they breathe in does not flow in a smooth path causing vibrations with the membranous parts of the airway.
Snoring can be induced through a variety of factors which include consumption of alcohol, sleep deprivation, the position in sleep, and the anatomy of a person’s mouth. While snoring is not a disease, it is a symptom of a disorder known as “sleep apnea.” It is a condition in which a person is not able to sleep properly due to poor breathing and obstruction of their airway. About 40% of men and 24% of women suffer from habitual snoring, and an estimated 22 million Americans suffer from sleep apnea. (source)
8. What are skin tags, and why do they appear on certain people more than others?
Skin tags are small, harmless tumors that form in areas where the skin rubs against itself. Parts of our bodies where the skin folds, like eyelids, armpits, the groin, or breasts are more likely to be affected by skin tags. They’re usually painless and non-cancerous and do not grow over time. Skin tags are more common in women than in men. Almost 45% of people have skin tags on their body.
There is no definite cause known for the formation of skin tags. Some studies show the presence of low-risk HPV 6 and 11 in skin tags, which might be a cause of their formation. The development of skin tags can be related to various different factors including genetics, high insulin levels, and even pregnancy. (source)
9. Why does your eyesight get worse with age?
Apart from genetics, there are several factors that make our eyes get weaker over time. An adult between the age of 19 to 40 enjoys the best vision. Most problems related to vision are due to genetics, but, there are several other factors that cause our vision to deteriorate as we age.
Presbyopia is a part of the natural aging process. It makes the lenses in our eyes hard which weakens the ability of our eyes to change focus. This lens-hardening is caused due to decreasing levels of alpha-crystalline. It is considered a type of refractive error where a person is not able to focus on nearby objects, especially in low-light conditions. Ability to focus on nearby objects deteriorates as we age. As a child, we can focus on objects as near as 50 mm. As we grow older, this distance increases to 100 mm by the age of 25, and then to about one to two meters above the age of 60. The risk of developing presbyopia increases after the age of 35, and almost everyone is affected by the condition to some extent.
Some other factors which affect our eyesight daily are exposure to shorter wavelengths of visible light and UV light. Constant and prolonged exposure to these types of light can cause vision impairment. Apart from that, smoking is considered really harmful to your vision. According to studies, an individual who smokes is twice as likely to develop AMD as a non-smoker. The probability of developing cataracts is three times that of non-smokers. Smoking causes deposits of heavy metals such as cadmium in the lens of our eyes which can lead to such problems. (source)
10. Why do toilets at our homes have a tank on the back but public toilets do not?
If you’ve ever wondered why public toilets do not have a tank like the toilets at our homes, it is because of the different flushing mechanism they use. Toilets operate using a siphon. It is a tube that is connected to the bottom of the bowl which creates suction and drains the bowl when we press the lever. Toilets at our homes are attached to a tank which stores water and fills the bowl causing the contents to be forced out of of the bowl. Home toilets bowels are not attached directly to a water pipeline, which is why a tank is required to aid the mechanism and create the pressure when the bowl is flushed. Whereas public toilets are directly attached to a water pipeline, and when we press the lever, it opens the valve and allows the water to enter the bowl with the required force that creates the pressure to help drain the bowl. (source)