271. What is used to prevent freezing of fuel in space crafts?
1. Benzene
2. Glycol
3. Acetylene
4. Ester
Option “B” is correct Glycol is an organic compound with the formula (CH2OH)2. It is used to prevent freezing of fuel in space crafts.
272. _________ is the major component of natural gas.
1. Acetone
2. Methane
3. Chlorine
4. Hexane
Option “B” is correct Methane is a chemical compound with the chemical formula CH₄ and it is a major component of natural gas.
273. Carbon dioxide is produced by all of the following except –
1. Burning fossil fuels
2. Global warming
3. Cement production
4. Automobiles
Option “B” is correct Global warming, also referred to as climate change, is the observed century-scale rise in the average temperature of the Earth’s climate system and its related effects. Carbon dioxide is a one of the Green House gas which cause global warming. Carbon dioxide is not produced by Global warming.
Option “D” is correct Hydralazine is used to cure high blood pressure (hypertension).
275. For what is Mohs scale used?
1. To measure brightness of a substance
2. To measure viscosity of a liquid
3. To measure elasticity of a material
4. To measure hardness of minerals
Option “D” is correct The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs.
276. The nuclear force is –
1. Short range repulsive force
2. Short range attractive force
3. Long range repulsive force
4. Long range attractive force
Option “B” is correct Nuclear forces are short range attractive forces that bound the nucleus against the repulsive electrostatic force between Protons.
277. Which of the following contain carbon?
1. Lignite
2. Tin
3. Silver
4. Iron
Option “A” is correct Coal minerals are divided mainly into four types on the basis of the percentage of Carbon amount- Peat – 40-55%, Lignite – 45-65%, Bituminous -65-85% and Anthracite – more than 85%.
Option “A” is correct Polytetrafluoroethylene (PTFE) is usually known as Teflon. PTEF is a solid fluorocarbon. Its density is 2.2 g/cm3 and its melting point is 327°C. This is especially used for making a non-stick surface coating for utensils.
Option “A” is correct Nitrous Oxide is commonly known as laughing gas.
280. Polymer of Natural Rubber is-
1. Ethylene
2. Isoprene
3. Acetylene
4. Hexane
Option “B” is correct Polymerization is the process of joining together a large number of small molecules to make a number of the very large molecule. Natural rubber is the natural polymer of Isoprene.
