1. Which gas is known as ‘noble gas’?
(a) Hydrogen
(b) Oxygen
(c) Helium
(d) Carbon dioxide
[M.P. P.C.S. (Pre) 2016]
Ans. (c) Helium
- The noble gases are a group of elements with similar characteristics.
- They are all odorless, colorless, single-atom gases that hardly react with other substances.
- These elements don’t usually mix with anything else when conditions are ideal.
- The six gases that are found in nature are –
- Helium
- Neon
- Argon
- Krypton
- Xenon
- The Radioactive Radon
|
2. Percentage amount (by volume) of which one of the following gases is lowest in the atmosphere?
(a) Argon
(b) Carbon dioxide
(c) Nitrogen
(d) Oxygen
[R.A.S./R.T.S.(Pre) 2007]
Ans. (b) Carbon dioxide
- The air contains a mixture of gases, some of which are pollutants and gases that trap heat.
- The most common gas is nitrogen, making up 78%, followed by oxygen (20.95%) and argon (0.93%).
- Carbon dioxide is present in the atmosphere in small amounts (0.03%).
|
3. What is the approximate percentage of Nitrogen present in the atmosphere?
(a) 10-11%
(b) 18-20%
(c) 40-42%
(d) 78-79%
[M.P.P.C.S. (Pre) 2006]
Ans. (d) 78-79%
- The air has many gases, mostly in small amounts, including some pollution and gases that trap heat.
- The gas that takes up the most space in the air is nitrogen at 78%, oxygen is second at almost 21%, and argon is third at 0.93%.
- Carbon dioxide makes up only 0.03% of the atmosphere.
|
4. Which gas is not in the gaseous cycle?
(a) N2
(b) O2
(c) Carbon
(d) H2
(e) None of these
[Chhattisgarh P.C.S. (Pre) 2014]
Ans. (d) H2
- Biogeochemical cycles can be divided into two categories:
- Gaseous (with air or water as the source)
- Sedimentary (with the Earth’s crust as the source)
- Gaseous cycles involve Nitrogen, Oxygen, Carbon and Water, whereas sedimentary cycles involve Iron, Calcium, Phosphorus, Sulphur, and other elements that stay near the Earth
|
5. Which of the following pairs of gases is used for the respiratory activities of divers?
(a) Oxygen and Helium
(b) Oxygen and Neon
(c) Oxygen and Nitrogen
(d) Oxygen and Argon
[U.P. R.O./A.R.O. (Mains) 2016, U.P. P.C.S. (Mains) 2014]
Ans. (a) Oxygen and Helium
- Deep sea divers wear tanks with a combination of oxygen and helium.
- Helium makes it easier to breathe underwater because it does not create as much airway resistance as air.
- It does not dissolve in the water like nitrogen so it won’t get into their bloodstream.
|
6. Which gas is mixed with Oxygen for respiration by divers in the deep sea?
(a) Helium
(b) Nitrogen
(c) Xenon
(d) Ammonia
[R.A.S./R.T.S.(Pre) 2007]
Ans. (a) Helium
- Deep sea divers carry tanks filled with a blend of oxygen and helium.
- Helium is easier to breathe than air, so it takes less effort to fill their lungs.
- Helium also doesn’t mix with water as much as other gases, like nitrogen, so it doesn’t get into the bloodstream even when underwater.
|
7. Which one of the following mixtures of gas is used by the deep sea divers?
(a) Mixture of Helium-Oxygen
(b) Mixture of Helium-Nitrogen
(c) Mixture of Oxygen-Acetylene
(d) Mixture of Oxygen – Hydrogen
[U.P. Lower Sub. (Pre) 2004]
Ans. (a) Mixture of Helium-Oxygen
- Deep sea divers have cylinders filled with a combination of oxygen and helium.
- Helium has less airway resistance than air and takes less energy to breathe in.
- It is not as soluble in water as other gases, like nitrogen, meaning it won’t enter the bloodstream even when under pressure.
|
8. What is the shape of the sulphur hexafluoride molecule?
(a) Trigonal pyramid
(b) Octahedral
(c) Planar
(d) Tetrahedral
[43rd B.P.S.C. (Pre) 1999]
Ans. (b) Octahedral
- Sulphur hexafluoride (SF6) is a non-flammable chemical that is colorless, odorless, and inorganic.
- It is made up of six fluorine atoms surrounding one sulphur atom.
- It is a molecule with more than the usual amount of bonding sites.
|
9. Easily soluble in water –
(a) Carbon
(b) Nitrogen
(c) Ammonia
(d) Iodine
[U.P.P.C.S. (Pre) 1993]
Ans. (c) Ammonia
- Ammonia is a polar molecule which can easily dissolve in water.
- This happens because the hydrogen atoms in ammonia are attached to a very electronegative (electrically charged) nitrogen, and the hydrogen atoms in water molecules are attached to a very electronegative oxygen atom.
- Ammonia and water are both polar molecules and are able to do hydrogen bonding, so they mix together very well.
|
10. Which is used as Laughing gas –
(a) Nitrous oxide
(b) Nitrogen dioxide
(c) Nitrogen trioxide
(d) Nitrogen tetroxide
[U.P.P.C.S. (Mains) 2011, U.P.U.D.A./L.D.A. (Mains) 2010, 40th B.P.S.C. (Pre) 1995]
Ans. (a) Nitrous oxide
- Nitrous oxide, also known as laughing gas, is a colorless gas that has a slight metal smell and taste.
- When it is breathed in, it can cause confusion, happiness, numbness, trouble with coordination, dizziness, and eventually make a person lose consciousness.
- It is also used as a gas to help people go to sleep during medical procedures.
|
11. The ‘laughing gas’ is :
(a) Hydrogen peroxide
(b) Nitrous oxide
(c) Carbon monoxide
(d) Sulphur dioxide
[M.P.P.C.S. (Pre) 2017]
Ans. (b) Nitrous oxide
- Nitrous oxide, commonly referred to as laughing gas, is a colorless gas that has a slight metallic smell and taste.
- When people inhale it, it can cause them to feel disoriented, happy, numb, uncoordinated, dizzy, and eventually pass out.
- It is also used as a type of anesthesia.
|
12. Which of the following is also known as laughing gas?
(a) Nitric oxide
(b) Nitrous oxide
(c) Nitrogen pentoxide
(d) Nitrogen
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (b) Nitrous oxide
- Nitrous oxide is a gas that can make people laugh, and it is called ‘laughing gas’.
- It has no colour and has a slight metallic smell and taste.
- If someone breathes it in, it can make them feel giddy, confused, numb and lightheaded, and eventually make them pass out.
- It is also used in medicine to put people to sleep
|
13. Laughing gas used as anaesthesia by doctors is –
(a) Nitrogen
(b) Nitrogen oxide
(c) Nitrous oxide
(d) Nitrogen dioxide
[44th B.P.S.C. (Pre) 2000]
Ans. (c) Nitrous oxide
- Laughing gas, which is used by doctors as an anaesthetic, is actually called nitrous oxide.
|
14. Which one of the following is also called Stranger Gas?
(a) Argon
(b) Neon
(c) Xenon
(d) Nitrous Oxide
[I.A.S. (Pre) 2008]
Ans. (c) Xenon
- Xenon is a type of gas and can be identified by its symbol Xe and atomic number 54.
- It is very rare, has no smell, no colour, no taste and is not usually involved in chemical reactions.
- It is sometimes called ‘stranger gas’ because there is only a tiny amount of it in the air (0.08 parts per million).
- It was discovered by two chemists, William Ramsay from Scotland and Morris Travers from Kingston.
|
15. Which one of the following is not correct?
(a) Bordeaux mixture is a mixture of copper (II) sulphate and calcium hydroxide in water and is used as a fungicide.
(b) Boric acid is used in the pharmaceutical industry and also as a food preservative.
(c) Dry ice is solid carbon dioxide
(d) Nitric oxide is a laughing gas.
[U.P.P.C.S. (Mains) 2010]
Ans. (d) Nitric oxide is a laughing gas
- NO is not the same as the gas that makes you laugh.
- That gas is actually called N2 O and the other options given are correct.
|
16. Discharge of nitrogen causes –
(a) Increase in the amount of atmospheric nitrogen
(b) Increase in the amount of nitrogen in the lithosphere
(c) The amount of nitrogen in the lithosphere and in the atmosphere is unchanged
(d) Destruction of nitrifying bacteria
[U.P.P.C.S. (Mains) 2008]
Ans. (c) The amount of nitrogen in the lithosphere and in the atmosphere is unchanged
- The nitrogen cycle is a process that turns nitrogen into different forms.
- This is accomplished through both living organisms and physical processes.
- It includes things like fixing, turning into ammonium, nitrification, and denitrification.
- Denitrifying bacteria turn nitrate and nitrite into nitrogen gas, and this gas is released back into the air and ground, so the overall amount of nitrogen stays the same.
|
17. Which one of the following is the permanent gas in the atmosphere?
(a) Carbon dioxide
(b) Ozone
(c) Nitrogen
(d) Neon
[U.P. P.C.S. (Mains) 2017]
Ans. (c) Nitrogen
- Permanent gases can not be turned into liquids and stay as gases in their natural environment.
- Examples of these gases are –
- Hydrogen
- Nitrogen
- Carbon monoxide
- Nitrogen is a permanent gas and is the main component of the atmosphere, making up around 78%.
|
18. The gas used to inflate the tyres of an aircraft is –
(a) Hydrogen
(b) Nitrogen
(c) Helium
(d) Neon
[U.P.R.O./A.R.O. (Pre) 2014, Uttarakhand U.D.A./L.D.A. (Pre) 2007]
Ans. (b) Nitrogen
- Nitrogen gas is put in the tyres of airplanes.
- This is because it doesn’t help fire catch and spread, and it can stop the wheels from getting too hot when the aircraft lands (landing and going fast can make the temperature really high).
- There are other advantages, but it’s the cheapest kind of gas that won’t help a fire.
|
19. In order to compensate for the deficiency of which of the following elements, the insectivorous plants trap and eat insects?
(a) Manganese
(b) Nitrogen
(c) Magnesium
(d) Sulphur
[U.P.R.O./A.R.O. (Mains) 2013]
Ans. (b) Nitrogen
- Some plants can catch and eat insects and other tiny creatures in order to get the nitrogen they need to survive.
- Most plants get the nitrogen they need from the soil.
|
20. The soil in which insectivorous plants grow is deficient in :
(a) Magnesium
(b) Calcium
(c) Nitrogen
(d) Water
[U.P. P.C.S. (Mains) 2016]
Ans. (c) Nitrogen
- Insectivorous plants don’t get their nitrogen from the soil because they live in wet, swampy areas where nitrogen is scarce.
- Instead, they get their nitrogen from small insects.
- These plants have adapted so they can get their nutrition in this way.
- Examples of insectivorous plants are –
- Nepenthes
- Dionea
- Drosera
- Utricularia
|
21. Which gas is usually filled in the balloon?
(a) Hydrogen
(b) Oxygen
(c) Carbon dioxide
(d) Helium
[M.P. P.C.S. (Pre) 1991]
Ans. (d) Helium
- A gas balloon can fly because it is filled with a gas lighter than air.
- Usually, helium is used as it is not combustible when mixed with air.
|
22. Helium is preferred to Hydrogen in air balloons because it –
(a) Is cheaper
(b) Is less dense
(c) Has greater lifting power
(d) Does not form an explosive mixture with air
[U.P.P.C.S (Pre) 2011]
Ans. (d) Does not form an explosive mixture with air
- Helium is chosen for air balloons over hydrogen because it is not reactive.
- Additionally, hydrogen is very combustible and could cause danger, so it is not a safe choice.
|
23. Tear gas is :
(a) Ammonia
(b) Chlorine
(c) Hydrogen Carbide
(d) Hydrogen Sulphide
[Uttarakhand P.C.S. (Pre) 2002]
Ans. (b) Chlorine
- Tear gas is a chemical weapon that causes pain and discomfort, including in the eyes, skin, and respiratory system.
- It can even cause blindness.
- It is typically used by police to control riots.
- Alpha Chloroacetophenone, 2-chlorobenzalmalononitrile, acrolein, and chlorine are the most common chemicals used for tear gas.
- The nitrogen cycle is a process of changing nitrogen into different forms, which can happen naturally or by using physical processes.
- The nitrogen cycle includes fixing, ammonifying, nitrifying, and denitrifying.
- Denitrifying bacteria turn nitrate and nitrite into nitrogen, and the amount of nitrogen in the environment stays the same.
|
24. Which one of the following is the permanent gas in the atmosphere?
(a) Carbon dioxide
(b) Ozone
(c) Nitrogen
(d) Neon
[U.P. P.C.S. (Mains) 2017]
Ans. (c) Nitrogen
- Permanent Gases are gases that can’t be turned into liquids and stay as a gas under typical conditions.
- Hydrogen, nitrogen, and carbon monoxide are all examples of these gases.
- Nitrogen is a permanent gas and makes up about 78% of the air.
|
25. The gas used to inflate the tyres of an aircraft is –
(a) Hydrogen
(b) Nitrogen
(c) Helium
(d) Neon
[U.P.R.O./A.R.O. (Pre) 2014, Uttarakhand U.D.A./L.D.A. (Pre) 2007]
Ans. (b) Nitrogen
- Aeroplanes use nitrogen gas in their tyres because it stops the tyres from catching fire when the plane lands.
- This is because oxygen would support combustion which is dangerous.
- Although there are other advantages, nitrogen is the cheapest gas that does not cause fires.
|
26. In order to compensate for the deficiency of which of the following elements, the insectivorous plants trap and eat insects?
(a) Manganese
(b) Nitrogen
(c) Magnesium
(d) Sulphur
[U.P.R.O./A.R.O. (Mains) 2013]
Ans. (b) Nitrogen
- Certain plants eat insects and other small animals in order to get the nitrogen they need to grow.
- Most plants can get enough nitrogen just from the soil.
|
27. Which of the following gas is used as tear gas –
(a) H2
(b) SO2
(c) NH3
(d) Cl2
[43rd B.P.S.C. (Pre) 1999]
Ans. (d) Cl2
- Some plants eat insects and other small animals to get the nitrogen they need to survive.
- Usually they get the nitrogen they need from the ground, but some need to eat bugs to get it.
|
28. The foul smell of dead fish is due to the compound
(a) Amino compounds
(b) Aldehydic compounds
(c) Sulphur compounds
(d) Nitro compounds
[Jharkhand P.C.S. (Pre) 2016]
Ans. (a) Amino compounds
- Trimethylamine is an amino compound in which the three hydrogen atoms of ammonia are replaced by three methyl groups.
- It has a strong smell, like that of dead fish, which comes from these compounds.
|
29. Which of the following remains in a solid state at normal temperature?
(a) Chlorine
(b) Bromine
(c) Iodine
(d) Fluorine
[Jharkhand P.C.S. (Pre) 2003]
Ans. (c) Iodine
- The Group Seven elements are often referred to as halogens.
- They are fluorine, chlorine, bromine and iodine, and they all have 7 electrons in their outer shell.
- Iodine is a dark blue-black material with a shiny surface, so it stays in a solid form at regular temperatures.
|
30. The most reactive among the halogens is –
(a) Fluorine
(b) Chlorine
(c) Bromine
(d) Iodine
[I.A.S. (Pre) 1997]
Ans. (a) Fluorine
- The halogens (Fluorine, Chlorine, Bromine, Iodine, Astatine) are non-metal elements that are very electrically negative and reactive.
- Fluorine is the smallest atom of the halogens and it is the most reactive because it has the strongest ability to pull electrons away from other elements.
|
31. Bromine is a :
(a) Colourless gas
(b) Brown solid
(c) Highly inflammable gas
(d) Red liquid
(e) None of the above/More than one of the above
[63rd B.P.S.C. (Pre) 2017]
Ans. (d) Red liquid
- Bromine is a part of the halogen family.
- At room temperature it is a red-brown liquid that turns to gas easily.
|
32. Which one of the following elements exists in a liquid state at room temperature?
(a) Hydrogen
(b) Oxygen
(c) Bromine
(d) Iodine
[U.P. P.C.S. (Mains) 2017]
Ans. (c) Bromine
- Bromine is a chemical element with the symbol Br and atomic number 35.
- It is the third lightest halogen and is a red-colored liquid that does not freeze at room temperature like other non-metallic elements.
|
33. The halogen being used as analgesic is –
(a) Chlorine
(b) Bromine
(c) Iodine
(d) Fluorine
[R.A.S./R.T.S.(Pre) 2012]
Ans. (b) Bromine
- Pain-relieving drugs work in different ways on the nerves in our body and in our brain.
- Bromine compounds are used to treat pain.
|
34. Which one of the following non-metals is not a poor conductor of electricity?
(a) Sulphur
(b) Selenium
(c) Bromine
(d) Phosphorus
[I.A.S. (Pre) 2007]
Ans. (b) Selenium
- Selenium is a non-metal that changes its electrical conductivity when exposed to light or other electromagnetic radiation.
- It comes in different forms that can be changed by changing the temperature or the speed of heating and cooling.
- Selenium, which is element number 34, was first discovered by the Swedish chemist Jons Jacob Berzelius in 1817.
|
35. The most commonly used substances in fluorescent tubes are –
(a) Sodium Oxide and Argon
(b) Sodium Vapor and Neon
(c) Mercury Vapor and Argon
(d) Mercuric Oxide and Neon
[U.P.P.C.S. (Pre) 2006]
Ans. (c) Mercury Vapor and Argon
- A fluorescent lamp tube usually has a low-pressure air mixture of mercury vapor and argon inside of it.
- Sometimes other gases like xenon, neon, or krypton can also be used.
- The pressure inside the lamp is about 0.3% of the air pressure we’d experience outside.
|
36. Which gas is filled in normal tube lights?
(a) Sodium vapour with argon
(b) Sodium vapour with neon
(c) Mercury vapour with argon
(d) Mercury vapour with neon
[M.P. P.C.S. (Pre) 1993]
Ans. (c) & (d) Mercury vapour with argon & Mercury vapour with neon
- Regular tube lights contain mercury vapor and a type of gas like argon or neon.
- When an electric current passes through the gas, the mercury vapor is activated and creates ultraviolet light.
- This ultraviolet light causes the phosphor coating inside the bulb to light up.
|
37. Which gas is filled at low pressure in a tube light?
(a) Argon and Neon
(b) Neon and Mercury vapour
(c) Nitrogen and Neon
(d) Only Argon
[Uttarakhand P.C.S. (Pre) 2005]
Ans. (b) Neon and Mercury vapour
- The regular tube lights contain mercury vapor mixed with an inert gas like argon or neon.
- When an electric current runs through the gas, it excites the mercury vapor and produces ultraviolet light.
- This light causes the phosphor coating inside the tube to glow.
|
38. Tubelight is filled with –
(a) Sodium vapour
(b) Argon gas at low pressure
(c) Mercury vapour at low pressure
(d) Mercuric oxide & Argon gas
[U.P. Lower Sub. (Pre) 2009]
Ans. (b) & (c) Argon gas at low pressure & Mercury vapour at low pressure
- Regular tube lights contain a mixture of mercury vapor and an unreactive gas such as argon or neon.
- When electricity is applied, this creates a reaction in the mercury vapor which emits short-wave ultraviolet light.
- This causes the phosphor coating inside the bulb to generate light.
|
39. The gas used in discharge tubes for optical decoration and advertising is –
(a) Carbon dioxide
(b) Ammonia
(c) Sulphur dioxide
(d) Neon
[U.P.P.C.S. (Pre) 2001]
Ans. (d) Neon
- Neon gas is utilized in discharge lamps, tubes, and fluorescent light bulbs.
|
