Daily Quiz: UPSC Prelims Marathon – December 28

Statement 1 is correct. When white light passes from air into a glass prism, violet bends the most and red bends the least. The other colors are bent by an amount between violet and red. When the light exits the prism, the light is separated into the colors in the visible spectrum.

Statement 2 is correct. Refraction is the bending of light (it also happens with sound, water and other waves) as it passes from one transparent substance into another.

Statement 3 is correct. When you see a rainbow, the Sun is always behind, and the center of the circular arc of the rainbow is in the direction opposite to that of the Sun. Because a rainbow is formed when a raindrop cause the light to have total internal reflection , this means the light is reflected back in the direction it originally came from hence you can only see a rainbow if your back is facing the sun.

Common Bases

• Aluminum hydroxide (Al[OH]3): antacids, deodorants
• Ammonium hydroxide (NH4OH): glass cleaner
• Calcium hydroxide (Ca[OH]2): caustic lime, mortar, plaster
• Magnesium hydroxide (Mg[OH]2): laxatives, antacids
• Sodium bicarbonate/sodium hydrogen carbonate (NaHCO3): baking soda
• Sodium carbonate (Na2CO3): dish detergent
• Sodium hydroxide (NaOH): lye, oven and drain cleaner
• Sodium hypochlorite (NaClO): bleach

Statement 1 is correct. A concave lens is a diverging lens. When parallel rays of light pass through a concave lens the refracted rays diverge so that they appear to come from one point called the principal focus.

Statement 2 is correct. Convex lenses are referred to as converging lenses because they bend light toward a focal point whereas concave (diverging lenses) bend light away from a focal point.

Statement 3 is incorrect. Curving inward, concave lenses cause light to spread out, resulting in a smaller image for the viewer. Despite being less useful than convex lenses, concave lenses have several uses, including in eyeglasses and contacts, flashlights, peepholes, binoculars, telescopes, and in photography.

Carbohydrates, proteins, and fats are digested in the intestine, where they are broken down into their basic units:

• Carbohydrates into sugars
• Proteins into amino acids
• Fats into fatty acids and glycerol

The body uses these basic units to build substances it needs for growth, maintenance, and activity (including other carbohydrates, proteins, and fats). These nutrients also differ in how quickly they supply energy. Carbohydrates are the quickest, and fats are the slowest.

We see non-luminous objects because light is reflected from them into our eyes. The Earth, like the moon, is a non-luminous object. It does not produce its own light. Astronauts on the moon can see the Earth because light from the Sun is reflected into the eyes.

Luminous objects are responsible for our vision. Example – Example: Lighted candle, torch bulb, the sun and stars. Sun also emits light as a result of fusion of Hydrogen atoms. Hence they are considered as luminous objects.

Arteries carry pure blood from the heart to supply all the tissues except for pulmonary artery.

Arteries branch out to form capillaries which supply oxygenated blood to all the organs. Arteries have thick walls as blood in them flows under great pressure. Arteries do not have any valves in them.

Veins carry deoxygenated blood to the heart and the lungs except for pulmonary veins. Veins are formed by many capillaries joining together to dump the deoxygenated blood from different tissues. Veins have thin muscular walls as blood in them flows under less pressure.

Statement 1 is incorrect. According to the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in 2008, CFLs may pose an added health risk due to the ultraviolet and blue light emitted.

Statement 2 is correct. CFLs, like all fluorescent lamps, contain mercury as vapor inside the glass tubing. Because mercury is poisonous, even these small amounts are a concern for landfills and waste incinerators where the mercury from lamps may be released and contribute to air and water pollution.

Statement 3 is correct. It has a very long lifespan, compared to the normal incandescent bulb. CFLs typically have a rated service life of 6,000–15,000 hours, whereas standard incandescent lamps have a service life of 750 or 1,000 hours.