Lime juice contains 6-10 per cent of citric acid. Cement is a complex mixture of calcium silicates and calcium aluminates. When drops of lime juice fall on the floor, a chemical change takes place. One of the products is calcium citrate which gives a white colour on these spots.
Lotus leaf does not get wet due to our layers of cells in the epidermal layer of leaves. They contain cellulose, which get converted to cutin by the process of cutinization and form an impermeable membrane on the cell wall known as cuticle.
Cuticle is a layer of wax-like substances which are simple lipids containing one molecule of fatty acids esterifies with one molecule of long-chain alcohols instead of glycerol. A molecule of wax consists of odd number of carbon atoms ranging from C25 to C35. These are highly insoluble in water and chemically inert because these do not have double bonds in their hydrocarbon chains. Hence waxes form a protective covering. The formation of wax will be more in lotus leaf and hence being impermeable, it won’t allow the leaf to get wet.
The epidermal cells of the aerial parts of the plant very often deposited with a layer of fatty material called cutin on their exposed wall surface. It is actually made up of two layers namely inner cutinized layer, a layer of cellulose encrusted with cutin and outer cuticularised layer, a layer consisting of cutin ad crusted on the cell wall. When the cuticle is of considerable thickness, its chemical nature often varies in different plants, at least proportionally and may include cutin and wax. Since this layer is resistant to decay, and to microbes, in all the land plants it may have protective function and also prevent surface evaporation. In the case of aquatic plants like lotus, in the outer surface of the upper epidermis of floating leaves there is a conspicuous deposit of wax.
It is found as a thick layer on the surface of the cuticle. It is this wax that gives the bloom to these glaucous leaves and also resists wetting. So when water is spilled over this surface it will roll down and will not form a film over the leaf surface. If this unwetting property is not found, this film of water when happens to cover the leaf surface will close all the stomata, which will affect the gaseous exchange in this floating leafed plant, which has stomata only on the upper surface of the leaves. It is one kind of Hydrophytic adaption.
The unwettability prevents the retention of water on the leaf surface and thereby reduce the water weight which otherwise cause the submerging of the leaf instead of floating.
Yes, though only for a few minutes, and only if the eclipse is occurring just as the Moon is rising and the Sun is setting, or the Moon is setting and the Sun rising. A total eclipse occurs when the Earth is between the Moon and Sun, which are directly opposite to each other in the sky.
Seeing both the Sun and eclipsed Moon at the same time would appear to be a geometrical impossibility, but because the atmosphere has a lensing effect, it raises the images of both the rising Moon and setting Sun above the horizon for a few minutes.
For the same reason, day and night are not exactly equal at the time of the fall equinox, because the day is artificially lengthened a few minutes at each end by the refractive effect of the atmosphere, for a total of seven minutes. It is not until three or four days later that the day equals the night.
It is easier to see the scallop of a partial eclipse above the horizon at sunrise or sunset than it is to see a total eclipse, because the Sun is so much brighter than the Moon.
The rings around Saturn were first identified by astronomer Galileo Galilei in 1610. It was, however, Dutch Physicist Christian Huygens, who in 1659, recognized them as a broad, flat, thin ring, separated from the body of the plant.
In 1675, the Italian Astronomer G.D. Cassini identified two rings around it. Until 1969, it was believed that there were just three rings around Saturn “A”, “B”, and “C” and 151; “A” being the outermost and “C”, close to the planet. In 1969, the fourth ring was discovered by Pierre Guoria and soon, another one was also identified.
Pioneer satellite Data (1971) had indicated that was one more ring (“F”). French Astronomer, Edourd Albert Roche in 1849 postulated that the rings were the remnants of satellite that strayed too close to Saturn and due to which reason, disintegrated. His theory was that, if a satellite approaches, it’s primary, closer than a certain distance (known as “Roche Limit’ & 151; 2.44 times the radius of the planet), the satellite would break up and the broken pieces would gradually get distributed around the planet in a circular path.
The distances of the rings of Saturn are within the “Roche limit”. This would suggest that the rings are the remnants of a disintegrated satellite only.
The present thinking is that the rings are made up of countless small objects (varying in size from very small grains to small chunks of rocky material, covered by ice) and that each revolves around Saturn in its own orbit like a satellite.
That the rings contain particulate matter has been confirmed by the fact that Rings “A” and “C” exhibit certain transparency due to which, the body of Saturn could he seen through them, as also the light from the stars.
Furthermore, the satellites of Saturn are not completely eclipsed too, when they pass into the shadow of the rings. Very little information is available as to the precise composition of the matter in the rings. As per the observations of C.P. Kupier (1952), the Infra Red Spectrum is similar to the reflection spectrum of hoar-frost.
It is quite likely that these particles must have been of much bigger size earlier (even some metres in diameter), but these might have been a continuous reduction in their sizes due to their abrasion with objects like the meteoroids. Scientists are of the view that the continuous erosion may ultimately (at a far distant future) result in the rings slowly vanishing forever!
The overall appearance of the Moon is bright ash grey caused by the dark and bright barren rocky land, where there is no atmosphere. When viewed in a naked eye or through a telescope, there are vast basins called seas, which were filled with molten lava millions of years ago. These are the low land plains appearing dark or dusky for the naked eyes. During the final ending phase of volcanism on the Moon, numerous crators had liberated enormous quantity of glowing gases and mineral vapours through their vents, which had blown in all directions over the surface, depositing the mineral condensates in the form of micron-size glassy spherules, tear drops and other powdery forms.
The Lunar surface is full of these bright rays like deposits, which scatter-reflect the sunlight quite effectively giving it a bright appearance on surface. The combined effect of rocks and soil along with the crators and minerals like calcium, aluminum and titanium therefore give a silvery appearance to the naked eye.
The Moon revolves around the Earth in a period of about 27 days; it also rotates once on its axis in the same time and so it always keeps the same face towards the Earth. This phenomenon is known as captured rotation.
Inspite of the fact that the Moon’s axial rotation is equal to its period of revolution round the Earth, we can actually examine more than the half of the total surface. The reason is that Moon travels round the Earth in an ellipse, not in a circle since it takes elliptical path, the rate of axial spin remains constant, whereas orbital velocity changes and moves fastest when closest to us.
We can thus see a little round alternate edges of the Moon. Also, the lunar orbit is tilted with reference to ours, so that the Moon is sometimes north and sometimes south of the mean plane, enabling us see some way beyond alternate poles. These minor shifts, known as Librations, allow us to examine four-sevenths of the total surface. The remaining three-sevenths of the Moon is permanently hidden from our inquiring eyes.
The time taken for the moon to turn on its axis once and the time taken for it to revolve once around the earth are the same. Hence the moon shows us the same face every night. This is called synchronisis rotation or captured rotation.
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