281. Indian Institute of Remote Sensing is situated-
1. In Ahmedabad
2. In Dehradun
3. In Sriharikota
4. None of the above
Option “2” is correct. Indian Institute of Remote Sensing is situated in Dehradun.
282. What is the minimum distance (in meters) required to hear an echo?
1. 10
2. 13
3. 17
4. 21
Option “3” is correct. Echo is a reflection of sound that arrives at the listener with a delay after the direct sound.The reflecting object must be more than 17m from the sound source for echo to be perceived by a person located at the source.
283. Why does a Black board appears black in colour?
1. It reflects black colour
2. It absorbs black colour
3. It reflects all colours
4. It absorbs all the colours
Option “4” is correct. A black board appears black because it absorbs all the colors of white light and reflects none.
284. Which of the following instrument is used to measure Soil Water Tension?
Option “4” is correct. A tensiometer in soil science is a measuring instrument used to determine the Soil water tension.Such tensiometers are used in irrigation scheduling to help farmers and other irrigation managers to determine when to water. It can also be used in the scientific study of soils and plants.
285. What is the SI unit of Force?
1. Pascal
2. Boyle
3. Newton
4. Watt
Option “3” is correct. The SI unit of Force is Newton. One Newton is equal to 1 kilogram meter per second squared.
286. Which one of the following is a bad Thermal Conductor?
1. Aluminum
2. Copper
3. Glass
4. Silver
Option “3” is correct. Glass is bad thermal conductor and is a good insulator.It has tightly held electrons which did not allow heat to flow through it.
287. Who invented first working laser?
1. A. H. Taylor
2. W. K. Roentgen
3. T. H. Mailman
4. Fred Morrison
Option “3” is correct. LASER (LIGHT AMPLIFICATION BY STIMULATED EMMISSION OF RADIATION)is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The first laser was built in 1960 by Theodore H. Maiman.
288. In the absence of the earth’s atmosphere, sky would appear-
1. Blue
2. Deep red
3. White
4. Black
Option “4” is correct. In absence of earth’s atmosphere, sky would appear black due to absence of scattering phenomena.
289. Temperature of distant luminous bodies can be determined by –
French 
English