1. low temperature
2. low humidity
3. high evaporation
4. extreme temperature
Option “2” is correct. Xeric condition refers to low humidity. Xeric environment is place where water is meager
222. The temperature of the filament of lighted electric bulb is generally:
1. 100°C to 500°C
2. 1000°C to 1500°C
3. 2000°C to 2600°C
4. 4000°C to 5000°C
Option “3” is correct. Light bulbs are manufactured with tungsten filaments because tungsten has an abnormally high melting temperature, A “standard” 75 or 100 watt 120 volt bulb, the filament temperature is around 2550 degrees Celsius.
223. Which mirror is used as a rear view mirror in vehicles?
1. Plain
2. Convex
3. Concave
4. Cylindrical
Option “2” is correct. A convex mirror gives a much wider field of view of the traffic at your back than a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.
224. The minimum height of a plane mirror to see the full size image of a person is equal to-
1. The height of the person
2. Half the height of the person
3. One-fourth the height of the person
4. Double the height of the person
Option “2” is correct. The minimum height of plane mirror to enable a person to see full image is ½ of his height.
Option “1” is correct. The conversion of light energy into electrical energy is based on the phenomenon called photovoltaic effect. Silicon is most widely used semiconductor material for constructing photovoltaic cell.
226.
1. A
2. B
3. C
4. D
Option “2” is correct. Kalpakkam is a small town in Tamilnadu . Narora is located on the bank of river Ganga in district Bulandshahar, Uttar Pradesh. Kakrapara atomic power station is a nuclear power station in India, which lies in the state of Gujarat. Trombay is a northeastern suburb in Mumbai, India. It is famous for Bhabha Atomic Research Centre (BARC).
227. Which one of the following thermometers is known as pyrometer?
Option “2” is correct. A pyrometer is a type of remote sensing thermometer used to measure the temperature of a surface. In the modern usage, it is a device that from a distance determines the temperature of a surface from the spectrum of the thermal radiation it emits, a process known as pyrometry.
228. The safest temperature for keeping food fresh in a refrigerator is-
1. 4°C
2. 8°C
3. 0°C
4. 10°C
Option “1” is correct. Refrigerator temperatures do not destroy pathogenic or spoilage microorganisms. The lower temperature slows the growth of microorganisms already in the food. According to international standards, the recommended temperature of the refrigerator is 36°F to 38°F (1.7°C to 3.3°C). Thus option (a) is correct.
229. Which instrument is used in submarine to see the objects above sea level?
Option “4” is correct. A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer’s current position
230. Why does food cook faster in a pressure cooker?
1. The increased pressure increases the boiling point.
2. Does not waste steam.
3. The food is cooked quickly by steam.
4. The water boils at constant temperature.
Option “1” is correct. The trapped steam increases the atmospheric pressure inside the cooker by 15 pounds per square inch (psi), or 15 pounds above normal sea-level pressure. At that pressure, the boiling point of water is increased from 212°F to 250°F. This higher temperature cooks food faster.
