Exp) Statement 1 is correct. Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines. It is a mixture of reducing fuel and oxidizing oxidizer is introduced into a combustion chamber, typically using a turbopump to overcome the pressure. As combustion takes place, the liquid propellant mass is converted into a huge volume of gas at high temperature and pressure.

Statement 2 is incorrect. The oxidizer is necessary for burning the fuel.

Statement 3 is correct. N2O4 (Nitrogen Tetra Oxide) is used as an oxidizer in the propellant.

Source) Science & technology by Ravi Agrahari; Chapter 7; page 154

Exp) Statement (c) is correct. A geosynchronous orbit is a high Earth orbit that allows satellites to match Earth's rotation. Located at 22,236 miles (35,786 kilometers) above Earth's equator, this position is a valuable spot for monitoring weather, communications and surveillance.

If the satellite orbits at the same speed that the Earth is turning, the satellite seems to stay in place over a single longitude, though it may drift north to south.

In this case, the satellite cannot be too close to the Earth that it would not be going fast enough to counteract the pull of gravity.

Geostationary orbits help us to find a solution to the disadvantages of LEO(low Earth orbit). Low Earth Orbit is used for things that we want to visit often with the Space Shuttle, like the Hubble Space Telescope and the International Space Station. This is convenient for installing new instruments, fixing things that are broken, and inspecting the damage. It is also about the only way we can have people go up, do experiments, and return in a relatively short time.

There are two disadvantages: first is that there is still some atmospheric drag and the second is, unlike GEO satellites, LEO satellites fly at a much faster pace because of their proximity to Earth. Due to which weather satellite wouldn't be very effective for us in India if it does not have a long dwell time over the Indian subcontinent. Dwell time = the time a satellite sits over one part of the globe.

Source)

Science and Technology by Ravi P. Agrahari; Chapter 6

http://www.polaris.iastate.edu/EveningStar/Unit4/unit4_sub3.htm

Exp) Statement 1 is incorrect. The Low Earth Orbit requires a large number of satellites for whole coverage. 

Statement 2 is correct. LEO can provide truly global coverage and efficient use of the spectrum. Due to lower path loss, the use of smaller terminals becomes possible. 

Statement 3 is correct. In LEO, the propagation delay is very low (10 milliseconds).

Source)

Science and Te3chnology by Ravi P. Agrahari

Chapter 6; page number 136

Exp) Geostationary Earth Orbit (GEO) satellite is the most popular type of communication satellite. If the orbit period of satellite exactly matches the orbital period of the earth at an altitude of 35,863 kilometers above the earth's surface and rotates in the equatorial plane of the earth with the angular velocity of 3075 meters per second, such an orbit is called geosynchronous orbit. 

The disadvantages of GEO:

1. It provides a relatively large propagation delay of 0.24 seconds. This affects the voice and time data protocol.
2. Relatively large path loss due to large distance traveled by the signal.
3. Relatively high launch cost.
4. The polar region and far northern and southern hemispheres are poorly served by geostationary satellites.

Source)
Science and Technology by Ravi. P Agrahari; chapter 6; page number 137

Exp) Those satellite or space missions we send across the earth's orbit(beyond 35, 786 kilometers) are called as High Earth Orbit satellites; e.g. Chandrayaan-i, Chandrayaan-ii, Mangalyaan-i, Aditya Mission.

Source)

Science and Technology by Ravi. P. Agrahari

Chapter 6; page number 137

Exp) Statement 1 is correct. The Indian Space Research Organisation (ISRO) and Jet Propulsion Laboratory (JPL) of NASA are jointly working on the development of NASA-ISRO Synthetic Aperture Radar (NISAR) mission. It is a Dual Frequency Synthetic Aperture Radar Imaging Satellite.

Statement 2 is incorrect.  NISAR is a dual-frequency (L & S Band) Radar Imaging Satellite. It will be the first radar imaging satellite to use dual-frequency. Data obtained from this satellite will be useful for variety of applications, which include natural resources mapping and monitoring, estimating agricultural biomass over the full duration of crop cycle, assessing soil moisture, monitoring of floods and oil slicks, coastal erosion, assessment of mangroves, surface deformation studies, ice sheet collapses and dynamics.

Source) Science & technology by Ravi Agrahari, chapter 7; page 147

Exp) Statement 1 is incorrect. It is a low temperature based technology. A cryogenic rocket engine is a rocket engine that uses a cryogenic fuel or oxidizer, that is, its fuel or oxidizer (or both) are gases liquefied and stored at very low temperatures.

Statement 2 is correct. Liquid hydrogen is used as fuel and liquid oxygen as an oxidizer in the propellant system. 

Statement 3 is incorrect. Cryotrocins is the real application of cryoelectronics, a branch deals with the research of superconductivity at very low temperatures.

Source) Science & technology by Ravi Agrahari, Chapter-7; page- 158

Exp) Both the statements are correct. A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion (hence ramjet), but whereas a ramjet decelerates the air to subsonic velocities before combustion, the airflow in a scramjet is supersonic throughout the entire engine. That allows the scramjet to operate efficiently at extremely high speeds. 

Scramjet engines are a type of jet engine, and rely on the combustion of fuel and an oxidizer to produce thrust. Similar to conventional jet engines, scramjet-powered aircraft carry the fuel on board, and obtain the oxidizer by the ingestion of atmospheric oxygen (as compared to rockets, which carry both fuel and an oxidizing agent). This requirement limits scramjets to suborbital atmospheric propulsion, where the oxygen content of the air is sufficient to maintain combustion.

Source) Science & technology by Ravi Agrahari, chapter 7 page 161

Explanation:

• At a height of 35863 km, it takes 24 hours for the satellite to orbit. This type of orbit is known as a geosynchronous orbit, i.e. it is synchronized with the Earth.

Explanation:

• Statement 1 and 2 is the Correct Answer:
• Low Earth Orbits satellites are often in a polar orbit at the latitude of 50-1500 kilometres and the orbital period in the range of 95-120 minutes.

Advantages of LEO:

• • It can provide true global coverage and efficient use of spectrum.
  • Due to lower path loss, the use of smaller terminals become possible.
  • The propagation delay is very low(10 milliseconds)

Explanation:

• Pair 1 is Correct: The Space Applications Centre (SAC) is an institution of research in Ahmedabad under the aegis of the Indian Space Research Organisation (ISRO).
• Pair 2 is Incorrect: The Vikram Sarabhai Space Centre is a major space research centre of the Indian Space Research Organisation, focusing on rocket and space vehicles for India's satellite programme. It is located in Thiruvananthapuram.
• Pair 3 is Incorrect: Satish Dhawan Space Centre is a rocket launch centre operated by the Indian Space Research Organisation. It is located in Sriharikota in Andhra Pradesh.

Explanation:

• Pair 1 is Correct: The Baikonur Cosmodrome is a spaceport located in an area of southern Kazakhstan. The Cosmodrome is the world's first and largest operational space launch facility
• Pair 2 is Incorrect: Cape Canaveral launching pad is located in Florida, USA.
• Pair 3 is Correct: The Guiana Space Centre is a French and European spaceport to the northwest of Kourou in French Guiana, a region of France in South America.
• Pair 4 is Incorrect: The Palmachim Airbase is an Israeli military facility and spaceport located near the cities of Rishon LeZion and Yavne on the Mediterranean coast. It is named after nearby Kibbutz Palmachim.

1. All of the above

Explanation:

• Statement 1 is Correct:  Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which are being developed by various space agencies. A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion. Thus it is known as Supersonic Combustion Ramjet or Scramjet.
• Statement 2 is Incorrect: Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric air as the Oxidizer. This makes the system much lighter, more efficient and cost-effective.
• Statement 3 is Incorrect: ISRO successfully conducted an indigenous scramjet engine test for the first time.

Explanation:

• Option B is the correct Answer: Indian Remote Sensing System comes under the purview of the Department of Space.

Explanation:

• Statement 1 is correct: The Country plans to construct a crew vehicle which can accommodate 2 or 3astronausts along with its GSLV Mk-3 launcher.
• Statement 2 is Incorrect: The Prime Minister of India in his Independence Day address announced that an Indian astronaut would go into space by 2022.
• Statement 3 is Incorrect: A proposal for manned space flight, at a budget of INR 12.4 billion, with the usage of a fully autonomous orbital vehicle carrying two or three crew members to 400 km low orbit orbit was proposed for seven days and back.