Gases and laws related to Gases MCQ Quiz - Objective Question with Answer for Gases and laws related to Gases - Download Free PDF

The correct answer is Gases.

Key Points

• Gases show the highest expansion when temperature is increased.
• This is because the molecules in a gas are much farther apart compared to solids and liquids.
• When the temperature increases, the kinetic energy of gas molecules also increases significantly.
• The increased kinetic energy causes gas molecules to move more rapidly and spread out, leading to higher expansion.
• This phenomenon is described by the Ideal Gas Law, which states that the volume of a gas is directly proportional to its temperature.
• Gases are highly compressible and can occupy the entire volume of their containers, which also contributes to their high rate of expansion.

 Additional Information

• Solids
  • Solids have a definite shape and volume.
  • The molecules in solids are tightly packed, resulting in very limited movement.
  • Due to the strong intermolecular forces, solids exhibit the least expansion when the temperature is increased.
• Liquids
  • Liquids have a definite volume but no definite shape.
  • The molecules in liquids are less tightly packed than in solids, allowing them to move more freely.
  • Liquids expand more than solids but less than gases when the temperature is increased.
• Plasma
  • Plasma is a state of matter similar to gas but consists of free electrons and ions.
  • It is formed at very high temperatures when gases are ionized.
  • Plasma is found in stars, including the sun, and in man-made devices like neon signs and plasma TVs.

The correct answer is Gases.

Key Points

• Gases exhibit the highest expansion among states of matter when temperature is increased due to their low intermolecular forces and high kinetic energy.
• When heated, the molecules in a gas move faster and spread out, leading to significant volumetric expansion compared to solids or liquids.
• The expansion of gases is governed by the ideal gas law, PV = nRT, where temperature (T) directly affects volume (V) at constant pressure.
• Unlike solids and liquids, gases have no fixed shape or volume, allowing for unrestricted expansion when thermal energy is added.
• The coefficient of thermal expansion for gases is significantly higher than for liquids and solids, making them highly sensitive to temperature changes.

Additional Information

• Thermal Expansion: The phenomenon of matter increasing in volume due to a rise in temperature, caused by increased molecular vibrations.
• Intermolecular Forces: Gases have weak intermolecular forces compared to solids and liquids, enabling greater expansion under heat.
• Ideal Gas Law: A fundamental equation in physics and chemistry where the relationship between pressure, volume, and temperature of gases is expressed as PV = nRT.
• Coefficient of Thermal Expansion: A measure of how much a substance's volume changes per degree of temperature increase; gases have the highest coefficient among states of matter.
• Real Gases vs. Ideal Gases: Real gases deviate from the ideal gas law at very high pressures or low temperatures, though the principle of expansion with heat remains applicable.

The correct answer is increase in temperature.

Key Points

• Adiabatic compression refers to the process where a gas is compressed without any heat exchange with its surroundings.
• During adiabatic compression, the work done on the gas increases its internal energy, leading to a rise in temperature.
• The temperature increase is due to the direct relationship between pressure, volume, and temperature in adiabatic processes governed by the ideal gas law.
• No heat is transferred in an adiabatic process, as the system is thermally insulated.
• Adiabatic compression is a key principle in thermodynamics and is utilized in applications like internal combustion engines and air compressors.

Additional Information

• Adiabatic Process: A thermodynamic process where no heat transfer occurs between the system and its surroundings.
• Ideal Gas Law: The relationship between pressure (P), volume (V), and temperature (T) of an ideal gas given by PV = nRT.
• First Law of Thermodynamics: Energy conservation principle stating that the change in internal energy of a system equals the heat added minus the work done.
• Applications: Adiabatic processes are used in designing engines, refrigeration cycles, and air compressors for efficient energy transformation.
• Polytropic Process: A general form of thermodynamic processes where heat transfer may occur, unlike adiabatic processes which are heat-insulated.

The correct answer is Equal volumes of gases at the same temperature and pressure contain an equal number of molecules..

Key Points

• Avogadro's Law states that equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.
• This law helps explain the behavior of gases under different conditions, establishing a relationship between volume and the number of gas molecules.
• It is mathematically expressed as V ∝ n (where V is volume and n is the number of moles of gas).
• Avogadro's Law is fundamental to understanding ideal gas behavior and is used in deriving the Ideal Gas Law.

Additional Information

• Ideal Gas Law
  • The Ideal Gas Law combines Avogadro's Law, Boyle's Law, and Charles's Law into one equation: PV = nRT.
  • Here, P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature in Kelvin.
  • This law assumes that gases behave ideally, meaning they have no intermolecular forces and occupy no volume.
• Boyle's Law
  • Boyle's Law states that the pressure of a gas is inversely proportional to its volume when temperature and the number of moles are constant: P ∝ 1/V.
  • It explains how gas pressure increases when the volume decreases, provided the temperature remains unchanged.
• Charles's Law
  • Charles's Law states that the volume of a gas is directly proportional to its temperature when pressure and the number of moles are constant: V ∝ T.
  • This law indicates that gas volume increases with an increase in temperature, provided pressure is constant.
• Gas Constant (R)
  • The gas constant (R) is a proportionality constant in the Ideal Gas Law, with a value of 8.314 J/(mol·K).
  • R is essential for calculations involving the Ideal Gas Law, linking pressure, volume, temperature, and the number of moles.

The correct answer is Option 1: The pressure (P), volume (V) and temperature (T) of a fixed quantity of gas are related by the equation PV/T = Constant..

Key Points

• The Ideal Gas Law is a fundamental equation in physical chemistry and thermodynamics that relates the pressure, volume, and temperature of an ideal gas.
• The equation is usually written as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.
• The Ideal Gas Law combines several simpler gas laws: Boyle's Law, Charles's Law, and Avogadro's Law.
• The law assumes that gases are composed of point particles that do not interact with each other except through elastic collisions.
• It is an approximation that works well under many conditions but deviates at high pressures and low temperatures where gases are not ideal.

Additional Information

• Boyle's Law:
  • States that the pressure of a given mass of gas is inversely proportional to its volume at constant temperature.
  • Mathematically, it is represented as P1V1 = P2V2.
• Charles's Law:
  • States that the volume of a gas is directly proportional to its temperature at constant pressure.
  • Mathematically, it is represented as V1/T1 = V2/T2.
• Avogadro's Law:
  • States that equal volumes of all gases at the same temperature and pressure contain the same number of molecules.
  • Mathematically, it can be written as V/n = k, where k is a constant.
• Ideal Gas Constant (R):
  • The value of the ideal gas constant R is approximately 8.314 J/(mol·K).
  • It provides the necessary link between the macroscopic measurements of gas properties and the microscopic theory of gases.

The correct answer is Neon.

Key Points

• Electric discharge in gases occurs when electric current flows through a gaseous medium due to the ionization of the gas.
• Depending on several factors, the discharge may radiate visible light.
• Different elements emit different wavelengths of light to return to their respective ground states, so the colours of the tubes are varied.
• These colours can be used to produce atomic emission spectra of the elements electrically excited.
• Using known values of emission spectra, one can perform a similar discharge test on an unknown gas, gather an emission spectrum from it, and determine which elements are in the unknown gas.

Additional Information

The correct answer is Non-combustible.

• Hydrogen and helium are the most commonly used lift gases.
• Although helium is twice as heavy as (diatomic) hydrogen, they are both so much lighter than air that this difference is inconsequential.
• Helium is the second lightest gas. For that reason, it is an attractive gas for lifting as well.
  • A major advantage is that this gas is Non-combustible.
  • Today helium is used instead of hydrogen since it is inert so non-flammable which makes things a lot safer. Hydrogen can ignite very easily when mixed with the oxygen of the surrounding air.

Key Points

• Hydrogen:
  • Hydrogen gas consists of Hydrogen molecules.
  • The molecule consists of two atoms.
  • The atom has only one electron.
  • The nucleus of the hydrogen atom consists of only one proton.
• Helium:
  • Helium is the second lightest atom.
  • One nucleus of a Helium atom consists of two protons and two neutrons.
  • Helium atoms do not combine into molecules.
  • That is why it is called an inert gas, which consists of free atoms.

The correct answer is Latent heat.

• The heat released at the time of condensation is called Latent heat.

Key Points

• Latent heat:
  • Latent heat is defined as the energy that is absorbed or released during a phase change of a substance.
• ​Latent heat of condensation:
  • The conversion of water vapour into the water which is caused by the loss of heat called Latent heat condensation.
  • Condensation depends upon the amount of cooling and the relative humidity of the air.

Additional Information

• Humidity:
  • Humidity is defined as the concentration of water vapour present in the air. 
• Evaporation:
  • Evaporation is the process by which water changes from a liquid to a gas or vapour.
• Sublimation:
  • Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the intermediate liquid state.

The correct answer is Nitrogen.

Key Points

• Bulbs are filled with chemically inactive gases like Nitrogen or Argon to prevent the oxidation of the tungsten filament used in the bulb.
• About Nitrogen:
  • It is a chemical element with the atomic number 7 and is denoted by the symbol (N).
  • Nitrogen gas constitutes 78 % of the Earth's Air.
  • Nitrogen is odorless, colorless, and generally considered an Inert Gas in Nature.
  • Nitrogen was discovered by chemist and physician Daniel Rutherford in 1772.
• ​

Additional Information

• Hydrogen:
  • The atomic number is 1 and is denoted by the symbol (H).
  • It was discovered by Henry Cavendish.
• Carbon dioxide:
  • The atomic number is 6 and is denoted by the symbol (CO₂).
  • It was discovered by Joseph Black.
• Halogens:​
  • Halogens are non-metals that do not exist in elemental forms. 
  • For example - Bromine, chlorine, fluorine, iodine etc. 

The correct answer is Boyle’s Law.

• According to Boyle’s Law at a constant temperature, the volume of a gas is inversely proportional to pressure.

Key Points

• Boyle’s Law
  • At constant temperature, the volume of a definite mass of a gas is inversely proportional to the pressure.
  • P. V = constantAdditional Information

• Charles’ Law:
  • At constant pressure, the volume of a fixed mass of a gas is directly proportional to its absolute temperature.
  • \(V ∝T\)
• Gay-Lussac’s Law
  • At constant volume, the pressure of a given mass of a gas is directly proportional to the temperature in Kelvin.
  • \(P∝{T}\)
• Graham’s Law of Diffusion
  • According to this law, the rate of diffusion of a gas is inversely proportional to the square root of its density.

The correct answer is Hydrogen.

Key Points

• The metal reacts with acids to form salt and hydrogen gas.
• Metals that are above in the reactivity series react with acid. The reactivity series in given in the tabular form below.

The correct answer is Charles's law.

Explanation:

• In 1787, Jacques Charles formulated Charles' Law or the Law of Volume.
• According to this law, at constant pressure, the volume of a given mass of gas is directly proportional to its temperature.
• This is mathematically represented as V/T = Constant, at constant pressure. 

• If the pressure remains constant, the volume of the given mass of a gas is directly proportional to its absolute temperature.

• i.e. V ∝ T

Additional Information

• Boyle's law:
  • For a fixed mass of gas at a constant temperature, the volume is inversely proportional to the pressure.
  • P∝1/V
  • PV = constant (If the temperature remains constant, the product of pressure and volume of a given mass of a gas is constant.)
• Avogadro's law:
  • Avogadro’s Law states that at constant temperature and pressure, all equal volumes of gases will have an equal number of molecules" which means 'V' is directly proportional to the 'Number of molecules'.​
• Joule's law:
  • The ratio of the energy consumed in mechanical work (W) and the heat generated (H) by that work remains constant.
  • J is Joule's constant. J = 4.186 joule/calorie

Concept:

Key Points

• In 1787, Jacques Charles formulated Charles' Law or the Law of Volume.
• According to this law, at constant pressure, the volume of a given mass of gas is directly proportional to its temperature.

i.e. V ∝ T
or V/T = constant
\( \Rightarrow \frac{{{V_1}}}{{{T_1}}} = \frac{{{V_2}}}{{{T_2}}}\)

​

Explanation:

• Charle's law is valid only when the pressure of the system is kept constant.
• Provided the pressure is kept constant, the gases when heated will achieve higher kinetic energy.
• The high kinetic energy of the molecules will help them to overcome the intermolecular forces in them and undergo expansion.
• Thus, increasing the temperature, the gases will undergo expansion, provided the pressure is kept constant.
• Decreasing the temperature,  gases will undergo compression, P kept constant.
• Hence, the volume becomes directly proportional to temperature.
• As volume is dependent on the pressure, altering it will thus cause a change in volume and the effect of temperature could not be understood.

Hence, Charles's law of observed at constant pressure.

Important Points

• Boyle's Law states that for a fixed mass of gas at a constant temperature, the volume is inversely proportional to the pressure.

PV = constant

• Increasing or decreasing the pressure will thus cause a change in volume and the effect of temperature could not be understood.
• Gases that obey the gas laws (Charles law, Boyles law, and Universal Gas Law) are called ideal gases.
• Gay-Lussac's law states that at constant volume, the pressure of a fixed amount of a gas varies directly with temperature.

P ∝ T

\(\frac{P}{T} = Const\)

The correct answer is Brown.

Key Points

• The fumes of NO2 are brown in colour. Nitrogen dioxide or NO₂ is a deep red-orange gas. It is poisonous.
• Nitric oxide is a colourless, flammable gas with a slight odour. Nitrogen dioxide is a deep red-orange gas that is poisonous but not flammable.
• NO2 is responsible for the reddish-brown colour of smog.
• At high concentrations, NO2 is highly toxic and can cause serious lung damage.
• The following health effects may occur immediately or shortly after exposure to Nitrogen Dioxide like it can burn the skin and eye with possible eye damage.
• Nitrogen oxides include nitrous acid and nitric acid. 

The correct answer is Radon.

1. Radioactivity is a nuclear phenomenon in which an unstable nucleus undergoes decay and is referred to as radioactive decay.
2. Three types of radioactive decay occur in nature : (i) α-decay (ii) β-decay (iii) γ-decay
3. Noble Gases
   1. There are six elements in Group 18 of the Periodic Table - Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr) , Xenon (Xe) and Radon (Rn) which were earlier termed as inert gases or rare gases.
   2. Both of these terms are now no longer used as they are not so rare and not completely inactive. They do show some chemical reactivity in the form of some xenon and krypton compounds and hence are termed as noble gases.
   3. Occurrence
      1. All the noble gases except Radon occur in the atmosphere. Xenon and radon are the rarest elements of the group.
      2. Radon is a radioactive element. Radon (²²²Rn) is a decay product of Radium (²²⁶Ra) and is obtained by pumping off the gas from radium chloride solutions. 
      3. They are the minor constituent of the air, the atmospheric abundance being ~ 1% by volume of which argon is the major constituent. Ne, Ar, Xe and Kr are obtained by fractional distillation of liquid air.
      4. Helium and sometimes neon is found in minerals of radioactive origin e.g., pitchblende, monazite, cleveite. The main commercial source of helium is natural gas to an extent of 2-7%.
      5. They have closed valence shell electronic configuration due to which they have the least tendency to react.
      6. The best-characterised compounds are those of xenon with fluorine and oxygen only under certain conditions and only with highly electronegative fluorine and oxygen.
   4. Uses: These gases have several uses. Argon is used to provide an inert atmosphere, helium is used in filling balloons for meteorological observations, neon is used in discharge tubes and fluorescent bulbs.