General science covers the broad foundational knowledge that underlies all scientific disciplines. It includes core concepts in the scientific method, basic physics, chemistry, biology, and earth science that every scientifically literate person should understand. Read more
Which bond shares electrons?
HardA covalent bond is a type of chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. By sharing their outermost electrons, atoms can achieve a stable electron configuration, similar to that of a noble gas. This is the primary type of bond found in organic molecules like DNA and water H_2O.
The covalent bond is what makes diamonds so incredibly strong. Every carbon atom in a diamond is covalently bonded to four other carbon atoms in a rigid three-dimensional structure, making it almost impossible to pull the atoms apart without extreme force!
What color is sky?
EasyThe sky appears blue because of a physical phenomenon called Rayleigh scattering. As sunlight reaches the Earth's atmosphere, it is scattered in all directions by the molecules of air and the various particles in the atmosphere. Blue light travels as shorter, smaller waves and is scattered more than the other colors, which is why we see a blue sky when looking in any direction away from the sun. During sunrise or sunset, the light has to travel through more of the atmosphere, scattering the blue and violet light away and allowing the longer-wavelength reds and oranges to reach our eyes.
If Earth had no atmosphere, the sky would look black even during the daytime, which is exactly how it looks to astronauts in space or on the Moon.
What are the building blocks of proteins?
MediumAmino acids are the "building blocks" of proteins. There are 20 different amino acids that combine in various sequences to create the vast array of proteins found in living organisms. Nine of these are considered "essential" because the human body cannot produce them and must get them from food.
The sequence of amino acids in a protein is determined by your DNA-if even one amino acid is out of place, the entire protein might not work correctly!
Which vitamin is known as the 'Sunlight Vitamin'?
EasyVitamin D is known as the "Sunlight Vitamin" because the human body produces it when skin is exposed to sunlight. Specifically, UVB radiation from the sun converts a cholesterol derivative in the skin into vitamin D3 (cholecalciferol). This fat-soluble vitamin is essential for calcium absorption, bone health, immune function, and cell growth.
Just 10-30 minutes of midday sunlight several times a week is usually sufficient to maintain healthy vitamin D levels for most people, though this varies based on skin color, latitude, season, and sunscreen use. Vitamin D deficiency can cause rickets in children (softening of bones) and osteomalacia in adults (bone pain and weakness). Very few foods naturally contain vitamin D-fatty fish (salmon, tuna, mackerel), fish liver oils, beef liver, cheese, and egg yolks are among the few sources. Many countries fortify milk, orange juice, and cereals with vitamin D. The vitamin was discovered in 1922 by Elmer McCollum, who named it D because it followed vitamins A, B, and C. There are two forms: D2 (ergocalciferol) from plants and D3 (cholecalciferol) from animals and sun exposure.
Which vitamin is found in citrus fruits?
EasyVitamin C (ascorbic acid) is found in high concentrations in citrus fruits like oranges, lemons, and grapefruits. it is essential for the repair of body tissues, the production of collagen, and the proper functioning of the immune system.
In the 18th century, British sailors were nicknamed "Limeys" because they were required to eat limes and lemons to prevent scurvy, a deadly disease caused by Vitamin C deficiency!
Which gas is used in the manufacture of vanaspati ghee?
HardHydrogen gas is used in the manufacture of vanaspati ghee through a process called "hydrogenation." During this process, liquid vegetable oils are reacted with hydrogen in the presence of a nickel catalyst to turn them into solid fats.
This process is also how margarine is made, though modern health concerns have led to a decrease in the use of partially hydrogenated fats!
Which metal is liquid?
MediumMercury (symbol Hg) is the only metal that is liquid at standard room temperature and pressure. It is also known as "quicksilver" due to its mobility and silver color. Because it has a high rate of thermal expansion that is constant over a wide range of temperatures, it was historically used in thermometers and barometers. However, mercury is highly toxic, and its use is being phased out in many applications.
Mercury is so dense that even heavy solid objects like iron or lead will float on its surface. If you were to place a 12-pound iron cannonball into a pool of mercury, it would bob on top like a piece of cork in water!
What is the small flap that prevents food from entering the trachea?
HardThe epiglottis is a small, leaf-shaped flap of cartilage at the base of the tongue that acts like a "switch." When you swallow, it folds down to cover the entrance of the trachea (windpipe), ensuring that food and liquid go down the esophagus into the stomach rather than into your lungs.
If you've ever had food "go down the wrong pipe," it's because your epiglottis didn't close fast enough!
What type of energy is stored in food?
MediumFood contains chemical energy, which is a form of potential energy stored in the chemical bonds of molecules like carbohydrates, fats, and proteins. When we eat, our bodies break these bonds through digestion and metabolism, releasing the energy to power our muscles, brain, and other organs.
The energy in food is measured in "Calories." One dietary calorie is actually equal to the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius! Most adults need about 2,000 to 2,500 of these "energy units" every day to stay alive and active.
What is the process of a liquid turning into a solid?
EasyFreezing (or solidification) is the phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point. For water, this occurs at 0^circC 32^circF.
Some liquids can actually be cooled below their freezing point without turning into a solid; this is called "supercooling" and results in a liquid that freezes instantly if disturbed!
What type of bond involves sharing electrons?
MediumA covalent bond is a type of chemical bond where two atoms share one or more pairs of electrons. This usually happens between non-metal atoms. The shared electrons allow each atom to achieve a stable, full outer shell.
The bonds that hold together the atoms in a diamond are all covalent bonds, which is why diamond is the hardest natural material on Earth!
What is the sudden movement of snow down a slope?
EasyAn avalanche is a sudden and rapid flow of snow down a slope, such as a mountain. They can be triggered by natural factors like heavy snowfall or temperature changes, or by human activity like skiing.
A large avalanche can travel at speeds of up to 80 miles per hour and can carry enough force to snap mature trees like toothpicks!
What is the primary cause of tides?
EasyThe gravitational pull of the Moon is the primary cause of tides on Earth. The Moon's gravity "pulls" on Earth's oceans, creating a bulge of water on the side facing the Moon and another on the opposite side, resulting in high and low tides.
The Sun also exerts a gravitational pull on the oceans, but because it is so much farther away than the Moon, its effect on the tides is only about half as strong!
Which gas do humans breathe?
EasyOxygen O_2 is the gas that humans and most other living organisms need to breathe to survive. It is essential for the process of cellular respiration, where cells use oxygen to break down glucose and produce energy (ATP). While we inhale oxygen, our bodies produce carbon dioxide as a waste product, which we then exhale. Oxygen makes up about 21% of Earth's atmosphere, with the majority being nitrogen (78%).
Most of the oxygen we breathe doesn't actually come from trees or forests; between 50% and 80% of the world's oxygen is produced by oceanic plankton, algae, and some bacteria through photosynthesis.
Which state of matter has a definite volume but no definite shape?
EasyA liquid is the state of matter that has a definite volume but no definite shape. It takes the shape of its container but cannot be easily compressed. The particles in a liquid are close together but can move past each other, which allows the liquid to flow.
Water is the only substance on Earth that naturally exists in all three states-solid, liquid, and gas-within our normal range of temperatures!
How many Earths could fit inside the Sun?
HardApproximately 1.3 million Earths could fit inside the Sun if it were a hollow sphere. If you only look at the diameter, you could line up about 109 Earths across the face of the Sun.
The Sun is so large that it contains 99.8% of all the mass in the entire solar system!
Which country produces the most wind energy?
HardChina currently produces the most wind energy in the world, followed by the United States and Germany. China has invested heavily in renewable energy to power its massive population and industry.
China has more wind power capacity than the next several countries combined!
Which element has the symbol 'O'?
EasyOxygen is represented by the chemical symbol 'O' on the Periodic Table. It is a highly reactive nonmetal and an oxidizing agent that readily forms oxides with most elements. Oxygen is essential for the respiration of almost all complex life forms on Earth.
While we breathe in oxygen, it actually only makes up about 21% of the air in Earth's atmosphere!
What is the use of natural resources without depleting them called?
EasySustainability (or sustainable development) is the practice of using natural resources in a way that meets the needs of the present without compromising the ability of future generations to meet their own needs. It involves balancing environmental, social, and economic goals.
The concept was famously defined in the 1987 Brundtland Report, which urged the world to live within the limits of nature!
What is the cooling of water vapor into liquid called?
EasyCondensation is the process by which water vapor (gas) cools down and turns back into liquid water. This is how clouds form in the sky and why "dew" appears on grass in the morning. It is the opposite of evaporation.
You can see condensation in action when you breathe on a cold window and it fogs up-your warm breath is cooling down and turning into tiny liquid droplets!
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