Category Science

What is this common substance that is made of polar molecules and is lighter as a solid than it its liquid form?

One of water’s important properties is that it is composed of polar molecules. The two hydrogen atoms and one oxygen atom within water molecules (H2O) form polar covalent bonds. While there is no net charge to a water molecule, the polarity of water creates a slightly positive charge on hydrogen and a slightly negative charge on oxygen, contributing to water’s properties of attraction. Water’s charges are generated because oxygen is more electronegative, or electron loving, than hydrogen. Thus, it is more likely that a shared electron would be found near the oxygen nucleus than the hydrogen nucleus. Since water is a nonlinear, or bent, molecule, the difference in electronegativities between the oxygen and hydrogen atoms generates the partial negative charge near the oxygen and partial positive charges near both hydrogens.

Water is not attracted to everything. Because water molecules are polar, they are more attracted to molecules that are also polar or that have a charge (like an ion). Some kinds of molecules, like oils and fats, are nonpolar. These nonpolar molecules have no charge, and so water is not very attracted to them. 

Molecules of nonpolar compounds, such as oil and gasoline, even when mixed well into water, tend to separate from the water when the mixing stops. Water molecules tend to hold on to each other and squeeze out nonpolar oil and gasoline. Because of density differences between water and oil, this means that they form two separate liquid layers. For example, in oil-based salad dressings, the oil and water components separate into two layers and require mixing before being used. 

 

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What is the science studying pollen, spores, cysts and types of plankton in both fossil and living form called?

Palynology, scientific discipline concerned with the study of plant pollen, spores, and certain microscopic planktonic organisms, in both living and fossil form. 

The term is commonly used to refer to a subset of the discipline, which is defined as “the study of microscopic objects of macromolecular organic composition (i.e., compounds of carbon, hydrogen, nitrogen and oxygen), not capable of dissolution in hydrochloric or hydrofluoric acids”. It is the science that studies contemporary and fossil palynomorphs, including pollen, spores, orbicules, dinocysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedimentary rocks and sediments. Palynology does not include diatoms, foraminiferans or other organisms with siliceous or calcareous exoskeletons.

Palynology as an interdisciplinary science stands at the intersection of earth science (geology or geological science) and biological science (biology), particularly plant science (botany). Stratigraphical palynology, a branch of micropalaeontology and paleobotany, studies fossil palynomorphs from the Precambrian to the Holocene.

 

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Which is the outer part of the sun’s atmosphere, at hundreds of degrees higher temperature than the surface?

Our Sun is surrounded by a jacket of gases called an atmosphere. The corona is the outermost part of the Sun’s atmosphere.

The corona is usually hidden by the bright light of the Sun’s surface. That makes it difficult to see without using special instruments. However, the corona can be seen during a total solar eclipse.

The corona reaches extremely high temperatures. However, the corona is very dim. Why? The corona is about 10 million times less dense than the Sun’s surface. This low density makes the corona much less bright than the surface of the Sun.

The corona’s high temperatures are a bit of a mystery. Imagine that you’re sitting next to a campfire. It’s nice and warm. But when you walk away from the fire, you feel cooler. This is the opposite of what seems to happen on the Sun.

Astronomers have been trying to solve this mystery for a long time. The corona is in the outer layer of the Sun’s atmosphere—far from its surface. Yet the corona is hundreds of times hotter than the Sun’s surface.

A NASA mission called IRIS may have provided one possible answer. The mission discovered packets of very hot material called “heat bombs” that travel from the Sun into the corona. In the corona, the heat bombs explode and release their energy as heat. But astronomers think that this is only one of many ways in which the corona is heated.

 

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How refrigerator works?

Just a few minutes after you put warm food in a refrigerator, the food feels cooler. The refrigerator carries the heat from the food into the room outside.

How does a refrigerator do this? When a liquid changes to a gas it evaporates. As it evaporates, it takes heat from the things around it. Also, when a gas changes to a liquid, it condenses, and gives off heat. 

Refrigerators are cooled by a special liquid that is easily turned into a gas and then back to a liquid. First, the cool liquid is pumped to tubes inside the refrigerator, where it evaporates. As the liquid changes to a gas, it takes heat from the air inside the refrigerator. This makes the refrigerator cooler.

Then the warm gas is pumped into tubes outside the refrigerator, where it condenses. As the gas changes back to a liquid, it gives off heat. When the liquid cools, it is pumped back into the refrigerator. There it evaporates again. In and out it goes, carrying heat from the refrigerator and keeping the food cold.

Do you ever feel chilled when you get out of the bath or after swimming? This is because the water on your skin is evaporating off your body. It goes into the air where you can’t see it. As this happens, it takes heat away from your body, making you feel chilled.

Water vapour in the air sometimes clings to objects. On a hot day water vapour sticks to a cold glass of water. As more vapour sticks to the glass, it condenses, forming droplets of water on the outside of the glass.

 

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What are homoeothermic animals?

Living organisms thrive in different kinds of habitats, including acquatic environments. An important factor that helps some creatures adapt to changes in the external environment is the regulation of their internal environment – physiological processes. And body temperature plays a crucial role in this adaptation. As you may be aware, warm-blooded animals – such as birds and mammals – are those that maintain a high body temperature, and this temperature does not change with any change in the environment. On the other hand, cold blooded animals – such as fish, amphibians, and reptiles – tend to have temperatures that change depending on their surroundings. While warm blooded animals are generally called homeotherms, cold-blooded animals are called poikilotherms. And then there are heterotherms. These are creatures – such as some species of birds and mammals – that generate their own body heat but whose temperatures are also regulated by their environment. They have variations in temperature within different regions of their body, and during different times of the year too. In such cases, the body temperature is usually warmest at the core and much lower in the extremities. For example, the feet of penguins are cold to match their surroundings so that their feet are not stuck to the ice they are on. But their core body temperature is conserved by warning the blood returning from the extremities. Also, during winters, penguins are said to have body temperatures lower than normal, and this helps them conserve energy. Though heterotherms are usually small creatures, a study has shown that the king penguin – a large bird weighing about 10 kg – too exhibits heterothermy.

 

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Is Sargassum seaweed harmful to humans?

In the centre of the North Atlantic Ocean, amidst the vast blue expanse, is a huge floating mat of brown seaweed called sargassum. These mats are quite common in the Sargasso Sea, a region around Bermuda. The region has been named after the seaweed. These floating mats of seaweed were first reported by Christopher Columbus in the 15th Century. But since 2011, the Atlantic Ocean has been witnessing massive sargassum blooms every year. It stretches nearly 9000 km from West Africa to the Gulf of Mexico. Scientists call this the Great Atlantic Sargassum Belt. The seaweed band has been getting bigger every year, posing a serious threat to marine life, coastal ecosystem and the fishing communities dependent on it.

Sargassum is a genus of large brown seaweed (a type of algae) that floats in island-like masses. The seaweed species found in the Great Atlantic Sargassum Belt include Sargassum natans and Sargassum fluitans. They have many leafy appendages, branches, and round, berry-like structures called pneumatocysts, which keep them buoyant and close to the surface. The seaweed band attracts fish, shrimp, crabs, birds, and turtles, providing essential habitats. The seaweed is in turn nourished by the excrement of these organisms. Even larger creatures find plenty to eat amid the sargassum.

While the seaweed can be a boon for marine wildlife under normal circumstances, too much of it can pose a huge problem. As sargassum decays it consumes the oxygen, creating low oxygen conditions that affect marine life. Coral reefs and seagrass ecosystems can suffer when high levels of sargassum change water chemistry and block organisms from moving freely. Thick mats can also block sunlight from reaching the ocean depths. The seaweeds often wash up ashore en masse and choke coastal ecosystems. As the seaweed rots, it releases foul-smelling hydrogen sulphide gas, causing respiratory illness in local populations. They also affect coastal tourism.

Recurrent blooms

Scientists are concerned over the recurrent blooms having become the new normal. They attribute it to various factors such as warming of the ocean due to climate change, discharge of nutrients (nitrogen and phosphorus) from agricultural run-off and wastewater originating from major river basins such as the Congo and the Amazon and the deposition of iron and nutrient-rich Saharan dust on the ocean. Scientists say that multidisciplinary research and international efforts are required to address this issue.

 

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