Author Topic: Sharpen Your General Knowledge  (Read 21537 times)

Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #255 on: September 14, 2011, 03:09:01 PM »
Did Dinosaurs and Humans Ever Coexist On Earth?

Dinosaurs and humans did not coexist on earth.

Dinosaurs first appeared in the Triassic period, about 220 million years ago, and disappeared at the end of the Cretaceous period, about 65 million years ago.

Modern humans (Homo sapiens) appeared only about 25,000 years ago.

Movies that show humans and dinosaurs existing together arc only Hollywood fantasies.
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"

Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #256 on: September 17, 2011, 05:33:54 PM »
What Is Radiation, Which Objects Emit Radiation, and How Is the Wavelength of Radiation Measured?

Radiation is energy emitted by a source such as a planet, star, or your own body.

We measure radiation in wavelengths. Radiation travels in rising and falling motions called waves, like waves in the ocean.

Wavelengths are measured from the tip of one wave to the tip of the next.

Our eyes can register light waves, which are relatively short, but wavelengths of other kinds of radiation are too short or too long for us to be able to see them.

Radiation waves can also be measured by frequency, or how many waves pass a point within a certain amount of time.

Imagine you are standing in the ocean with a stopwatch.

You time the waves, counting how many pass you within one minute. If three waves go by, the wave frequency is 3 cycles per minute.

Radiation is usually counted in cycles per second (cps): 1 kilohertz (kHz) = 1,000 cps, and 1 megahertz (mHz) = 1 million cps.
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Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #257 on: September 19, 2011, 11:09:27 AM »
Why Do Trees and Leaves Change Color In Autumn and What Causes the Color Change In Fall?

The leaf color changes of autumn result from a complex interplay of factors of temperature, sunlight and moisture, all dependent on timing.

Not all the processes are predictable, but it is known that sunny days and cool nights in late summer and early autumn make for a particularly bright display of reds.

The yellow display operates separately from the red display, though both result from a shutdown of photosynthesis.

Shorter days signal the development of a layer of cells at the base of the leaf, called the abscission layer, that cuts off the water supply and later severs the leaf.

This stops production of chlorophyll, the green chemical at work in photosynthesis.

The chlorophyll breaks down, unmasking pigments already present in a leaf that will “turn” yellow: the xanthophylls, or yellows, and carotenes, the same orangey-yellow chemicals found in vegetables like carrots.

Still another class of pigment, the anthocyanins, is manufactured more quickly as summer ends.

As the leaf is cut off from its circulation, its sugar is trapped in the leaf and turns into anthocyanins, which depending on the species can be red, purple or maroon.

Cool nights in autumn inhibit the loss of sugar from the leaves, but brilliant sunshine promotes the maximum sugar synthesis and its transformation into anthocyanins.

A mild to moderate drought also stimulates anthocyanin production.

Drought or stresses like insects early in the season have comparatively little effect on the eventual nature of the color display, but can cause premature browning and leaf loss.
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Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #258 on: September 19, 2011, 11:11:48 AM »
Why Does Black Tea Lighten or Change Color When You Add Lemon Juice and What Causes the Chemical Change?

The simple answer to why black tea changes color is that adding lemon juice alters the acidity of the tea and the color change is an indication of this.

The color change is the same way that litmus paper changes color.

A similar effect can be observed by substituting the tea with some cooked red cabbage juice.

Tea leaves are rich in a group of chemicals known as polyphenols that amazingly account for almost one-third of the weight of the dried leaf.

Both the color of the tea and much of its taste are due to these compounds.

One group of polyphenols, the thearubigins, are the red-brown pigments found in black tea and constitute between 7 percent and 20 percent of the weight of dried black tea.

The color of black tea is also influenced by the concentration of hydrogen ions in the water.

Thearubigins in tea are weakly ionizing acids and the anions, or negatively charged ions, they produce are highly colored. If the water used to brew tea is alkaline, the color of the tea will be deeper due to greater ionization of the thearubigins.

If lemon juice, which is an acid, is added to the tea, the hydrogen ions suppress the ionization of thearubigins, and that makes the tea lighter.

Interestingly, the theaflavins, the yellow-colored poly-phenols in black tea, are not involved in the change in color that is associated with a change in acidity.
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Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #259 on: September 22, 2011, 11:18:34 AM »
Why Are Bread, Potatoes, Rice, Sugar, and Diamonds Not Black In Color If They’re Made of Carbon?

The best way to explain is with an example.

Sodium reacts violently on contact with water, while chlorine is a highly toxic greenish-yellow gas.

However, sodium chloride, the compound which contains these two elements, is harmless common salt, showing the properties of an element are very different from the properties of that element’s compounds.

The black powder used to produce a photocopy is finely ground carbon in its elemental form.

The particles are extremely small and arranged at random. Any light which falls on them is absorbed and not re-emitted, so the powder looks black. The sandwich certainly contains carbon but not in its elemental form.

Here, it is combined with oxygen and hydrogen as carbohydrates.

These compounds have their own properties which are nothing like the properties of their constituent elements. The slices of bread emit light of many wavelengths reasonably well, so when we look at bread in daylight, it appears white.

Carbon is normally found as an amorphous solid, which means it lacks a definite crystalline structure. Because of this, and because of the position of certain electrons in the outer orbits of the carbon atom, light is absorbed and not re-emitted.

This means the carbon atoms in graphite, soot and carbon black appear black.

Diamond, which is also carbon, is normally clear, because its crystalline structure alters the electrons and their positions to create a colorless crystal. Diamonds can be colored if other atoms, usually metals, are present and alter the electron bonds to create blue, yellow, pink and green versions.

Carbon, as present in foodstuffs such as bread and potatoes, is in hydrated form, the carbon has been chemically bonded with water and so does not appear black.

To get the black carbon back you need to remove the water, usually by heating.

This is why burnt toast is black.

Sugar is also carbon and water. But add concentrated sulphuric acid and you’ll see black carbon appear as the acid efficiently sucks out the water.
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"

Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #260 on: September 22, 2011, 11:20:54 AM »
Why Does an Octopus Change Color?

Even though octopuses belong to a group of shellfish called mollusks, they have no outside shell. A tough skin, called a mantle, covers the octopus’ body. This mantle contains small bags of pigment, or coloring matter, which are connected to the animal’s nervous system.

Any outside stimulus that excites the octopus makes its skin change color. It can change to blue, purple, brown, red, gray, white, and sometimes even striped.
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"

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Re: Sharpen Your General Knowledge
« Reply #261 on: September 22, 2011, 11:23:02 AM »
What Is the Carbon Cycle and What Percentage of Organisms Are Made of Carbon?

To survive, every organism must have access to carbon atoms.

Carbon makes up about 49 percent of the dry weight of organisms.

The carbon cycle includes movement of carbon from the gaseous phase (carbon dioxide in the atmosphere) to solid phase (carbon-containing compounds in living organisms) and then back to the atmosphere via decomposers.

The atmosphere is the largest reservoir of carbon, containing 32 percent CO2.

Biological processes on land shuttle carbon between atmospheric and terrestrial compartments, with photosynthesis removing CO2 from the atmosphere and cell respiration returning CO2 to the atmosphere.
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Re: Sharpen Your General Knowledge
« Reply #262 on: September 22, 2011, 11:23:47 AM »
What Causes Grey Hair and How Does the Lack of Melanin Make My Hair Look White?

As people age, their bodies stop producing melanin, the pigment that colors hair.

Without melanin, hair becomes transparent, so you can see through to the air inside the hollow hair shafts.

The diffusion of the light through the air bubbles makes hair look white.

Hair dye works to hide the white because it stains the outside of the hair shaft.
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Re: Sharpen Your General Knowledge
« Reply #263 on: September 22, 2011, 11:28:10 AM »
Why Does Hair Turn Gray When We Get Old and How Long Does It Take for Our Hair to Turn Gray as We Age?

Gray, or white, is merely the base color of our hair.

Pigment cells located at the base of each hair follicle produce the natural dominant color of our youth.

However, as a person grows older and reaches middle age, more and more of these pigment cells die and color is lost from individual hairs.

The result is that a person’s hair gradually begins to show more and more gray.

The whole process may take between 10 and 20 years, rarely does a person’s entire collection of individual hairs, which, depending on hair loss, can number in the hundreds of thousands, go gray overnight.

Interestingly, the color-enhancing cells often speed up pigment production as we age, so hair sometimes darkens temporarily before the pigment cells die.
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Re: Sharpen Your General Knowledge
« Reply #264 on: September 26, 2011, 03:26:48 PM »
Why Do Some People Have Straight Hair and Others Have Curly Hair?

Every hair on your head or on your body is made up of a root, the soft, bulb-shaped section under your skin, and the shaft, the longer strand that sticks out of your skin.

If you were to cut a shaft of your hair from near the root and look at a cross-section of it under a microscope, it would have either of two shapes: round or flat. If it appears round, that means your hair will grow out straight; if that cross-section appears flat, that means your hair will grow at different rates in different places, making it curl or wave. The flatter the shaft, the curlier it will be. The shape of your hair shafts is determined by the shape of your parents’ hair shafts, for this is one of the characteristics you inherited from them.

Some people with curly hair are unhappy with it and have their hair straightened, while others with straight hair take “permanent waves” to make their hair curly. But both of these changes are only temporary, lasting only a short time, for the shape of the shaft cannot be changed, and as that person’s hair grows out, it will look the same as before the change.
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Re: Sharpen Your General Knowledge
« Reply #265 on: September 26, 2011, 03:28:14 PM »
Why Do Evergreen Trees Not Lose Their Leaves In the Fall?

Evergreen trees do not keep their leaves indefinitely, but rather may grow new ones before the old ones fall, or keep some and drop others over a period of time.

As any southern gardener can tell you, some broadleaf evergreens, like Magnolia grandiflora, drop their heavy leaves in a staggered cycle over the course of the year.

Some, like the live oak, may show a heavy leaf loss in early spring, but retain a few old leaves while the new ones develop.

There is also seasonal needle loss with evergreen species of conifers, like pine, spruce, and fir trees. The leaf drop is a normal process, not a disease. The older,
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"

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Re: Sharpen Your General Knowledge
« Reply #266 on: September 26, 2011, 03:28:57 PM »
Can Your Hair Change Color Overnight?

Your hair can and will change color when you are old, but this does not happen overnight.

Different hair colors, from blonde to black, are determined by the melanin, the coloring matter, in your hair cells. This melanin becomes part of your hair cells as they form in the roots. Gray hair starts to appear in older people when less melanin is deposited in the new hair cells as they form. Without this coloring matter, the hair becomes gray and then white.

Certain diseases can cause the body to stop or slow down the production of melanin. So might worry, shock, or deep sorrow.
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"

Offline Shamim Ansary

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Re: Sharpen Your General Knowledge
« Reply #267 on: September 26, 2011, 03:29:42 PM »
Why Are Black Eyes Black and Why Does a Bruise Change Color When It Heals?

Blood released from capillaries and trapped under the skin and breakdown products of hemoglobin in the blood are chiefly responsible for the coloration of black eyes and other bruises.

In the case of black eyes, old blood is never really black, but dark purple and green.

The color of the pooled blood is magnified by the loose and transparent skin around the eyes, making a bruise there darker than it is on other parts of the body.

The chemicals mainly responsible for the changing colors of bruises are a series of products of the breakdown of hemoglobin, the oxygen-carrying compound in red blood cells.

An important one is biliverdin, which is green. There may also be bilirubin, which is yellow-brown.

The timing of the breakdown and the mixing of colors are not fully predictable, but at first bruises are usually dark blue, purple or crimson.

The color gradually changes to violet, green, dark yellow and pale yellow and finally disappears.

In one study pathologists found that they could conclude only that a yellow bruise was more than eighteen hours old.
"Many thanks to Allah who gave us life after having given us death and (our) final return (on the Day of Qiyaamah (Judgement)) is to Him"