Day 5: Static Quiz on Science

Correct Answer: C, A secondary rainbow appears outside of a primary rainbow and develops when light entering a raindrop undergoes two internal reflections instead of just one (as is the case with a primary rainbow).
The intensity of light is reduced even further by the second reflection, so secondary rainbows are not as bright as primary rainbows.

Correct Answer: C, Statement 1: During summer, the deeper you dive, the colder the water gets. During winter the opposite happens. The frigid water actually gets relatively warmer the deeper you descend in a lake. The reason has to do with how water molecules arrange. As water cools, the molecules sink and pack tighter and tighter together (increasing density) until the temperature drops to nearly 4 degrees Celsius. At that point, the water molecules are heavier than the water at the surface (that is freezing), causing a topsy-turvy effect where warmer water is at the bottom.
Statement 2: The layer of ice that forms on top of a lake, pond, river, or stream provides some insulation that helps the waterbody retain its heat. This is similar to the insulation offered by Igloos made in the Northern pole.

Correct Answer : D
: Free radicals are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules.
According to Rice University, once free radicals are formed, a chain reaction can occur. The first free radical pulls an electron from a molecule, which destabilizes the molecule and turns it into a free radical.

That molecule then takes an electron from another molecule, destabilizing it and tuning it into a free radical. This domino effect can eventually disrupt and damage the whole cell.

The free radical chain reaction may lead to broken cell membranes, which can alter what enters and exits the cell.

Antioxidants are intimately involved in the prevention of cellular damage — the common pathway for cancer, aging, and a variety of diseases.
Antioxidants are molecules that can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Although there are several enzyme systems within the body that scavenge free radicals, the principle micronutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C.

Correct Answer: C, Memristors, which are considered to be a sub-category of resistive RAM, are one of several storage technologies that have been predicted to replace flash memory.

Memristors are important because they are non-volatile, meaning that they retain memory without power.

Memristors are a special type of resistive device that can both perform logic and store data.

A memristor is often compared to an imaginary pipe that carries water. When the water flows in one direction, the pipe’s diameter expands and allows the water to flow faster — but when the water flows in the opposite direction, the pipe’s diameter contracts and slows the water’s flow down.

If the water is shut off, the pipe retains its diameter until the water is turned back on. To continue the analogy, when a memristor’s power is shut off, the memristor retains its resistance value.

Scientists have developed a new type of neural network chip that can dramatically improve the efficiency of teaching machines to think like humans. The network is called- Reservoir Computing System.

Researchers from University of Michigan in the US created their system using memristors, which require less space and can be integrated more easily into existing silicon-based electronics.

Researchers used a special memristor that memorises events only in the near history. Inspired by brains, neural networks are composed of neurons, or nodes, and synapses, the connections between nodes.

Reservoir computing systems built with memristors can skip most of the expensive training process and still provide the network the capability to remember. This is because the most critical component of the system – the reservoir – does not require training.

For example, a system can process a new photo and correctly identify a human face, because it has learned the features of human faces from other photos in its training set.

Correct Answer: A, Shortwave radiation (visible light) contains a lot of energy; longwave radiation (infrared light) contains less energy than shortwave radiation (shortwave radiation has a shorter wavelength than longwave radiation).

Solar energy enters our atmosphere as shortwave radiation in the form of ultraviolet (UV) rays (the ones that give us sunburn) and visible light. The sun emits shortwave radiation because it is extremely hot and has a lot of energy to give off.

Once in the Earth’s atmosphere, clouds and the surface absorb the solar energy. The ground heats up and re-emits energy as longwave radiation in the form of infrared rays. Earth emits longwave radiation because Earth is cooler than the sun and has less energy available to give off. Greenhouse gases are good absorbers of longwave radiations.

Correct Answer: B Statement 1: Blue ice occurs when snow falls on a glacier, is compressed, and becomes part of the glacier. Air bubbles are squeezed out and ice crystals enlarge, making the ice appear blue. Small amounts of regular ice appear to be white because of air bubbles inside them and also because small quantities of water appear to be colourless.

In glaciers, the pressure causes the air bubbles to be squeezed out, increasing the density of the created ice.

Large quantities of water appear to be blue, as it absorbs other colours more efficiently than blue.
Therefore, a large piece of compressed ice, or a glacier, would appear blue.

Statement 2: The blue color is sometimes wrongly attributed to Rayleigh scattering, which is responsible for the color of the sky.

Rather, water ice is blue for the same reason that large quantities of liquid water are blue: it is a result of an overtone of an oxygen–hydrogen (O−H) bond stretch in water, which absorbs light at the red end of the visible spectrum.

Water molecules absorb other colors more efficiently than blue.

In the case of oceans or lakes, some of the light hitting the surface of water is reflected back directly, but most of it penetrates the surface, interacting with its molecules. The water molecule can vibrate in different modes when light hits it.

The red, orange, yellow, and green wavelengths of light are absorbed so that the remaining light is composed of the shorter wavelengths of blue and violet. This is the main reason why the ocean is blue. So, water owes its intrinsic blueness to selective absorption in the red part of its visible spectrum.

Correct Answer: A, As per the Standard Model of particle physics:

All matter around us is made of elementary particles, the building blocks of matter. These particles occur in two basic types called quarks and leptons.

There are four fundamental forces at work in the universe: the strong force, the weak force, the electromagnetic force, and the gravitational force. They work over different ranges and have different strengths. Gravity is the weakest but it has an infinite range. The electromagnetic force also has infinite range but it is many times stronger than gravity

Three of the fundamental forces result from the exchange of force-carrier particles, which belong to a broader group called “bosons”.

Correct Answer: C, The sound would travel fastest in the speed of sound in an ideal gas depends only on its temperature and composition.The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior.

However, the speed of sound varies from substance to substance: sound travels most slowly in gases; it travels faster in liquids; and faster still in solids. For example, (as noted above), sound travels at 343 m/s in the air; it travels at 1,484 m/s in water (4.3 times as fast as in air); and at 5,120 m/s in iron (about 15 times as fast as in air).

In an exceptionally stiff material such as diamond, sound travels at 12,000 meters per second (26,843 mph); (about 35 times as fast as in air) which is around the maximum speed that sound will travel under normal conditions.

Correct Answer: A, CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key (black). Opposed to this, there is another color mode RGB that is used mainly for web applications, and when the image is not to be printed.

In additive color models, such as RGB, white is the “additive” combination of all primary colored lights, while black is the absence of light.

In the CMYK model, it is the opposite: white is the natural color of the paper or other background, while black results from a full combination of colored inks.

When CMY “primaries” are combined at full strength, the resulting “secondary” mixtures are red, green, and blue. Mixing all three gives an imperfect black or a perfect grey.

To save cost on ink, and to produce deeper black tones, unsaturated and dark colors are produced by using black ink instead of the combination of cyan, magenta, and yellow

Correct Answer: A, Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as a solid called dry ice when frozen.

If the temperature and pressure are both increased from STP to be at or above the critical point for carbon dioxide, it can adopt properties midway between a gas and a liquid. At the supercritical state, it becomes a fluid.

More specifically, it behaves as a supercritical fluid above its critical temperature (31.10 °C) and critical pressure, expanding to fill its container like a gas but with a density like that of a liquid.

Supercritical CO2 is becoming an important commercial and industrial solvent due to its role in chemical extraction in addition to its low toxicity and environmental impact