Rocket Propulsion - Liquid Propellants Quiz(MCQ)

1 .

Which of the following propellants were used in the Titan mission?

A)

RP1

B)

RDX

C)

Aviation gasoline

D)

50% UDMH + 50% hydrazine

Correct Answer : 50% UDMH + 50% hydrazine

Explanation : UDMH is often used in mixed form with 30-50% of hydrazine. Titan missile and launch vehicle make use of this fuel combination.

2 .

Evaporation is a major concern for ________

A)

bipropellants

B)

solid propellants

C)

cryogenic propellants

D)

monopropellants

Correct Answer : cryogenic propellants

Explanation : Cryogenic propellants are stored at very low temperatures in their storage/propellant tanks. Even though they have significant performance, their maintenance is a complex and elaborate procedure. Because of their low boiling point vale, they evaporate quickly.

3 .

A good liquid propellant will have ________

A)

resistance to deterioration

B)

easy deterioration

C)

absorption of moisture

D)

small amount of impurities

Correct Answer : resistance to deterioration

Explanation : A good liquid propellant should have no appreciable absorption of moisture. It should also be resistant to deterioration as it may be required to be kept intact for a long period of mission journey.

4 .

Determine the density specific impulse (I_d) if the specific impulse is 315 s and the average density of the propellants is 840 kg/m³. Take the reference density to be the maximum density of water

A)

251.3 s

B)

264.6 s

C)

279.5 s

D)

304.4 s

Correct Answer : 264.6 s

Explaination : I_d = δ_avI_s, where I_s is the specific impulse and δ is the average specific gravity.
?_av = 840/1000 = 0.84, in which consider the density of water to be 1000 kg/m³.
I_d = 0.84x 315 = 264.6 s.

5 .

Which of the following is not a factor considered in the selection of liquid propellant for a rocket engine?

A)

Safety

B)

Economic

C)

Performance

D)

Injector pattern

Correct Answer : Injector pattern

Explanation : Injector pattern is not considered for the selection of liquid propellant. Economic, performance and safety reasons for choosing a propellant are perfectly reasonable.

6 .

Which of the following chemical particles cannot be suspended in liquid fuel to increase specific impulse?

A)

Boron

B)

Fluorine

C)

Beryllium

D)

Aluminium

Correct Answer : Fluorine

Explanation : Fluorine is highly toxic and corrosive. It may react with propellants as well. So it cannot be used.

7 .

Which among the following propellants is not corrosive?

A)

Nitric acid

B)

Liquid oxygen

C)

Liquid Fluorine

D)

Nitrogen tetroxide

Correct Answer : Liquid oxygen

Explanation : Liquid oxygen is a non-corrosive propellant. Nitric acid and nitrogen tetroxide are corrosive to some materials, but their extremely low temperature makes their storage and pumping a difficult task. Liquid fluorine is highly corrosive and toxic.

8 .

What is O-ring in a chemical rocket engine?

A)

A type of injector

B)

A type of pipe network

C)

A kind of seal

D)

A kind of control system

Correct Answer : A kind of seal

Explanation : O-ring is a kind of seal technology used in the pressure vessel industry. Liquid rocket engines might use O-ring for the purpose of sealing the propellant tanks.

9 .

Which of the following is not a desirable property of a liquid propellant?

A)

Low specific gravity

B)

Stability

C)

Low freezing point

D)

High specific heat

Correct Answer : Low specific gravity

Explanation : One of the desirable properties of a liquid propellant is that it should have high specific gravity. Specific gravity is the ratio of density of a substance to the density of a reference substance.

10 .

______ are not liquid oxidizers.

A)

Borohydrides

B)

Fluorinated hydrocarbons

C)

Oxygen-fluorine compounds

D)

Nitrogen-fluorine formulations

Correct Answer : Borohydrides

Explanation : Borohydrides are not liquid oxidizers. Rest of the options are storable, cryogenic liquid oxidizer propellants with high specific impulse values.

11 .

LOX boils at _______ atmospheric pressure.

A)

90⁹C

B)

90 F

C)

90 K

D)

90 R

Correct Answer : 90 K

Explaination : LOX refers to liquid oxygen. It boils at 90 K. Since their boiling point is very low, a cryogenic setup is required for the storage and transport of this oxidizer.

12 .

Which of the following is the specific gravity and heat of vaporization of LOX at atmospheric pressure?

A)

1.41; 231 kJ/kg

B)

1.80; 235 kJ/kg

C)

1.08; 253 kJ/kg

D)

1.14; 213 kJ/kg

Correct Answer : 1.14; 213 kJ/kg

Explanation : LOX refers to liquid oxygen. It has a specific gravity of 1.14. That means it is 1.14 times denser than water having a density of about 1000 kg/m3. It has a heat of vaporization of 213 kJ/kg.

13 .

Theoretical specific impulse of 90% H₂O₂ is _______

A)

114 s

B)

154 s

C)

204 s

D)

321 s

Correct Answer : 154 s

Explaination : 90% H₂O₂ has a specific impulse of 204s. Because of this good specific impulse, countries like USA, Russia and Germany used concentrated hydrogen peroxide for monopropellant gas generation before 1955.

14 .

Which of the following is not a catalyst used for H₂O₂ decomposition?

A)

Platinum

B)

Iron oxide

C)

Aluminium

D)

Manganese dioxide

Correct Answer : Aluminium

Explaination : Aluminium tanks are generally used for storing H₂O₂ for this reason. Whereas hydrazine is not compatible with iron, copper, its alloys, monel, magnesium, zine or some types of aluminium alloys.

15 .

In the combustion chamber, hydrogen peroxide decomposes to give ________

A)

water

B)

oxygen and water

C)

hydrogen and water

D)

hydrogen and oxygen

Correct Answer : oxygen and water

Explanation : Decomposition of hydrogen peroxide gives oxygen and water.
The reaction is represented as H₂O₂ → H₂O + 1/2O₂ + heat.

16 .

When are the tanks with cryogenic propellants pressurized?

A)

After the engine start

B)

10 sec after the engine start

C)

10 sec before the engine start

D)

Just before the engine start

Correct Answer : Just before the engine start

Explanation : This is done to ensure that the propellants are at its lowest possible temperature. Else they might evaporate within the tank and may lead to devastating results under wrong circumstances.

17 .

_______ is not liquid fuel.

A)

Xylidine

B)

Furfuryl alcohol

C)

Nitric acid

D)

Hydrazine hydrate

Correct Answer : Nitric acid

Explanation : Nitric acid is not a fuel, but and oxidizer. HNO₃ is also used as a very strong oxidizing agent in chemical reactions.

18 .

Which of the following is not a liquid fuel?

A)

Hydrogen peroxide

B)

Ammonia

C)

Ethyl alcohol

D)

Borohydrides

Correct Answer : Hydrogen peroxide

Explanation : Hydrogen peroxide (H₂O₂) acts as an oxidizer. Ammonia (NH₃), ethyl alcohol (C₂H₅OH), and Borohydrides (containing BH₄^–) are liquid fuels.

19 .

Petroleum derivatives are mainly _______ chemicals.

A)

gasoline

B)

alcoholic

C)

hydrocarbon

D)

aldehydic

Correct Answer : hydrocarbon

Explanation : Petroleum derivatives are hydrocarbon chemicals. This means that it is a compound made up of hydrogen and carbon.

20 .

H₂ burns with oxygen with a ________ flame.

A)

blue-yellow

B)

yellow-white

C)

yellow-orange

D)

colorless

Correct Answer : colorless

Explaination : When H₂ burns with oxygen, it produces a colorless flame. In reality, the flame is a pale blue that appears to be invisible in daylight.

21 .

RP-1 specific gravity at 15°C is ______

A)

0.65

B)

0.70

C)

0.75

D)

0.80

Correct Answer : 0.80

Explaination : RP-1 is a highly refined form of kerosene. It is alternatively called as Rocket Propellant-1 or Refined Petroleum-1. It has a specific gravity of 0.80 at a temperature of 15°C.

22 .

Methane is a ____ fuel.

A)

bipropellant

B)

monopropellant

C)

hypergolic hydrocarbon

D)

cryogenic hydrocarbon

Correct Answer : cryogenic hydrocarbon

Explanation : Methane falls under the category of cryogenic hydrocarbon fuels. Using methane or RP-1 have shown to give a small advantage in the performance of initial stages of space launch vehicles.

23 .

Carbon deposits on the inside of cooling passage can lead to __________

A)

increase in heat transfer and decrease in wall temperature

B)

decrease in heat transfer and increase in wall temperature

C)

increase in heat transfer and increase in wall temperature

D)

decrease in heat transfer and decrease in wall temperature

Correct Answer : decrease in heat transfer and increase in wall temperature

Explanation : Cooling passages by some means may have carbon deposits on its inside. This can lead to a decrease in heat transfer and an increase in the wall temperature. It happens because the operation of cooling passages is inhibited by the carbon deposits and as a result the cooling is ineffective.

24 .

Petroleum fuels form ________ radiating flames.

A)

yellow-white

B)

blue-green

C)

orange-red

D)

orange-yellow

Correct Answer : yellow-white

Explanation : The bright brilliant radiating flames of petroleum fuels are yellow-white in color. Main examples of petroleum fuels include kerosene, gasoline, gaseous fuels like methane, propane, butane etc.

25 .

Which of the following is not a hydrocarbon fuel?

A)

Diesel

B)

Kerosene

C)

Ethyl alcohol

D)

Turbojet fuel

Correct Answer : Ethyl alcohol

Explanation : Ethyl alcohol is not a hydrocarbon fuel. Kerosene and diesel are petroleum derivatives.

26 .

_______ is not a method of monopropellant ignition.

A)

Electrical

B)

Pulverization

C)

Flame heat

D)

Catalytic material

Correct Answer : Pulverization

Explanation : Pulverization for the sake of monopropellant ignition is not a possible method. Pulverization is the act of grinding a substance to powder or dust form.

27 .

______ is an excellent catalyst for hydrazine at room temperature.

A)

Iridium

B)

Zeolite

C)

Cobalt

D)

Antimony trioxide

Correct Answer : Iridium

Explanation : Iridium is an excellent catalyst for hydrogen decomposition reaction at room temperature. For faster startup, the catalyst can be reheated.

28 .

UDMH stands for _______

A)

Unsaturated Diethyl Hydrazine

B)

Unsaturated Dimethyl Hydrazine

C)

Unsymmetrical Diethyl Hydrazine

D)

Unsymmetrical Dimethyl Hydrazine

Correct Answer : Unsymmetrical Dimethyl Hydrazine

Explanation : UDMH is the short form of Unsymmetrical Dimethyl Hydrazine. Its chemical formula is (CH3)2NNH2. UDMH is often used instead of hydrazine because forms a more stable liquid at larger temperatures.

29 .

Standard commercial hydrazine has less than ________% aniline.

A)

0.5

B)

0.6

C)

0.8

D)

1.0

Correct Answer : 1.0

Explanation : Commercially available hydrazine has less than 1% aniline in it. It also has about 1.5% maximum weight of water and less than 10 mg/l of particulates, including carbon.

30 .

Hydroxylammonium nitrate has a specific impulse of ______

A)

10-65s

B)

100-165s

C)

200-265s

D)

300-365s

Correct Answer : 100-165s

Explanation : Hydroxylammonium nitrate is an example of a synthetic monopropellant. It is abbreviated as HAN. It has a specific impulse in between 200 and 265s.

31 .

Iron, nickel and cobalt can decompose hydrazine at ________ temperature.

A)

273 K

B)

289 K

C)

400 K

D)

450 K

Correct Answer : 450 K

Explanation : Hydrazine will be decomposed in the presence of iron, nickel or cobalt at elevated temperatures (about 450K). Here the temperature act as an agent for improving catalytic decomposition. Some of the other catalysts can do the same at room temperature.

32 .

In catalytic decomposition of hydrazine, it decomposes into ________ and _______

A)

ammonia; nitrogen

B)

hydrogen; nitrogen

C)

ammonia; hydrogen

D)

ammonium; nitrogen

Correct Answer : ammonia; nitrogen

Explanation : Hydrazine has a chemical formula of N2H4. It undergoes catalytic decomposition to give ammonia (NH3) and nitrogen (N2). Some forms of hydrazine include monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH).

33 .

The catalytic decomposition of hydrazine is an __________ reaction.

A)

exergonic

B)

endergonic

C)

exothermic

D)

endothermic

Correct Answer : exothermic

Explanation : Exothermic reactions involve the release of heat to the surroundings. Hydrazine undergoing catalytic decomposition is an example of exothermic reaction.

34 .

Ammonia decomposition into nitrogen and hydrogen gases is an _________ reaction.

A)

Exergonic

B)

Endergonic

C)

Endothermic

D)

Exothermic

Correct Answer : Endothermic

Explanation : The decomposition reaction in which nitrogen and hydrogen forms from ammonia is an endothermic reaction. In endothermic reactions, heat is absorbed from the surroundings for the reaction to take place.

35 .

Which of the following is not a gold gas propellant?

A)

Argon

B)

Hydrazine

C)

Nitrogen

D)

Freon 14

Correct Answer : Hydrazine

Explanation : Some of the cold gas propellants are Argon, Krypton, Freon 14 and Nitrogen. Reaction control systems typically use cold gas propellants. Hydrazine is a monopropellant.

36 .

For cold gas propellants, tank pressure is typically between __________ and __________

A)

100 Mpa; 500 Mpa

B)

200 Mpa; 1000 Mpa

C)

300 Mpa; 500 Mpa

D)

300 Mpa; 1000 Mpa

Correct Answer : 300 Mpa; 1000 Mpa

Explanation : The tank used for the storage of cold gas propellants typically have a pressure between 300 Mpa and 1000 Mpa. Cold gas propulsion is used typically for low thrust space propulsion purposes. Nitrogen is the most preferred cold gas propellant due to its lack of contamination, storage density and performance characteristics.

37 .

Use of stainless steel thruster helps in ______

A)

increase in specific impulse

B)

providing better orbital correction

C)

reduction of total power consumption

D)

elimination of reaction between propellants and thrusters

Correct Answer : elimination of reaction between propellants and thrusters

Explanation : Stainless steel eliminates the problem of propellant and thruster reaction. The propellants are initially stored at high pressure and when it reaches the exit nozzle, it will have low velocities before expansion.

38 .

How are forces from a cold gas thruster measured in a testing environment?

A)

Using load cells

B)

Using strain gage

C)

Using force balance

D)

Using accelerometers

Correct Answer : Using load cells

Explanation : Load cells aid in measuring the thrust produced by the cold gas thrusters. For example, PRSS (Pakistan’s first Remote Sensing Satellite) thrusters use FUTEK load cells for this purpose.

39 .

Which of the following gives a rough estimate of specific impulse provided by cold gas systems?

A)

10-50 s

B)

30-70 s

C)

80-150 s

D)

200-300 s

Correct Answer : 30-70 s

Explanation : Depending upon the propellant used, the specific impulse of the system will vary. For attitude control or orbital corrections, specific impulse required is lesser compared to other rocket engines. Hence the cold gas system provides less specific impulse.

40 .

Selection of propellant, storage tank, and RCS design depends on?

A)

Maximum thrust and storage tank mass and volume but not total impulse

B)

Mass and volume of storage tanks, maximum thrust and total impulse

C)

Maximum thrust and total impulse but not the storage tank mass or volume

D)

None of maximum thrust, total impulse or storage tank properties

Correct Answer : Mass and volume of storage tanks, maximum thrust and total impulse

Explanation : It depends upon all the three properties. In addition, it also depends upon the gas density, required maneuvers, flight duration and duty cycle.

41 .

Total impulses of cold gas systems are about _______ N-sec.

A)

400

B)

800

C)

1200

D)

1600

Correct Answer : 1200

Explanation : Cold gas systems can deliver total impulse having a magnitude of 1200 N-sec or 5000 lbf-sec. For higher total impulse values, liquid propellants are used.

42 .

Thrust in RCS is produced by the momentum exchange between exhaust and the _______

A)

pump

B)

injector

C)

payload

D)

spacecraft

Correct Answer : spacecraft

Explanation : Thrust generation is due to the exchange of momentum between exhaust and the spacecraft. The thrust is given by Newton’s second law F = mV_e.

43 .

For a short period of operation (lasting few minutes), the gas expansion in cold gas systems is ________

A)

adiabatic

B)

isothermal

C)

homogenous

D)

heterogeneous

Correct Answer : adiabatic

Explanation : Since the operation lasts only a short period of time, the expansion can be taken as adiabatic. It means that there is no heat absorption or release by the gas.

44 .

Use of solenoid valves increases power consumption for a cold gas propellant system.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

Explanation : In order to decrease power consumption, one can use solenoid valves. It requires an electric pulse to open and close and hence can be easily controlled with lesser power expended.