ECAT Entry Test Chemistry Gases MCQs

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Gases MCQS, Boyle’s Law, Charle’s Law, Gases Law, and Avogadro’s Law.

The behavior of gases under a variety of conditions is governed by different gas laws. One of the key concepts for the students who are preparing for the ECAT entry test is Chemistry gases explanations. This guide will go over Boyle’s Law, Charles’s Law, Avogadro’s Law, and Gay-Lussac’s Law, along with multiple-choice questions (MCQs) to test your knowledge. These laws play a key role in predicting the behavior of gases under changing pressure, temperature, and volume and are fundamental to many scientific theories and industrial applications.

ECAT Entry Test Chemistry Gases MCQs

Boyle’s Law: Pressure-Volume Relationship

Boyle’s Law assumes isothermal conditions such that the pressure of a given mass of confined gas is inversely proportional to the volume of the gas. Mathematically: The principle is widely spread across different daily phenomena, like breathing mechanisms and syringes, and also scuba diving where pressure differences affect gas behavior.

Charles’s Law: Temperature-Volume Relationship

Charles’s Law states that the volume of a gas is directly proportional to its absolute temperature (Kelvin scale), at constant pressure. The reason: This is why hot air balloons float up; when the temperature rises, the gas expands, decreasing density and making the balloon buoyant.

Avogadro’s Law: Volume-Mole Relationship

Avogadro’s Law states that under identical temperature and pressure, equal volumes of gases contain identical quantities of molecules. Mathematically: This law is important for gas reaction, as at standard temperature and pressure the molar volume (where 1 mol of any gaseous substance occupies) is 22.4 L.

Gay-Lussac’s Law: Pressure-Temperature Relationship

Gay-Lussac’s Law states that at constant volume, the pressure of a gas is directly proportional to its absolute temperature: This explains why sealed aerosol cans explode when heated, as pressure increases significantly with rising temperature.

Gases and Ideal Gas Law

The Ideal Gas Law combines Boyle’s, Charles’s, and Avogadro’s laws: Where:

  • = pressure,
  • = volume,
  • = number of moles,
  • = universal gas constant (8.314 J/mol·K),
  • = temperature (Kelvin). This equation helps in calculating unknown gas properties and understanding deviations in real gases.

MCQs on Chemistry Gases

1. Which of the following will have the same number of molecules at S.T.P?

  • 280cm³ of CO₂ and280cm³ of N₂Ocorrect
  • 28g of N₂ and 5.6dm³ of oxygen
  • 11.2 dm³ of O₂ and 32g of O₂

  • 44g of CO₂ and 11.2dm³ of CO

2. Choose the best example of diffusion of gases

  • Hot air rising above a candle
  • Vapour condensing on moist surface
  • Spreading of small from a scent bottle
    correct
  • Bubbling in soda bottle

3. If absolute temperature of a gas is doubled nd the pressure is reduced to one half, the volume of the gas will

  • Be doubled
  • Remains unchanged
  • Increase four times
  • Reduce to ¼correct

4. Which of the following elements will have strongest Van deer Wall force of attraction between its molecules?

  • Oxygen
  • Nitrogen
  • Chlorinecorrect
  • Hydrogen

5. The deviation of a gas from ideal behavior is maximum at:

  • 0°C and 2.0 atm
  • -10°C and 5.0 atm
    correct
  • 100°C and 2.0 atm
  • -10°C and 2.0 atm

6. the number of molecules in one dm³ of water is close to:

  • 55.6 x 6.02 x 10²³correct
  • 18/22.4 x 10²³
  • 6.20/22.4 x 10²³
  • 12.04/22.4 x 10²³

7. According to Boyle’s law at constant temperature, the product of pressure and volume of a given mass of gas is:

  • Multiple
  • Fraction
  • A constant
    correct
  • Whole number

8. if pressure remains constant _______, to which temperature the volume of a gas will become twice to what it is at 0°C.

  • 273K
  • 546K
    correct
  • 200°C
  • 546°C

9. The temperature recorded by Kelvin scale is:

  • 373 K
  • 273 K
    correct
  • 0K
  • None of these

10. How should the conditions be changed to prevent the volume of a given gas from expanding when its mass increased?

  • Temperate and pressure both are increased
  • Temperate and pressure both are lowered
  • Temperature is lowered and pressure increased
    correct
  • Temperature is increased and pressure is decreased

11. Equal masses of methane and oxygen are mixed in an empty container at 25°C. The fraction of total pressure exerted by oxygen is:

  • 1/3
    correct
  • 8/9
  • 16/17
  • 1/9

12. The order of the rate of diffusion of gases NH₃,SO₂,CI₂ and CO is

  • NH₃ > SO₂ > CI₂ > CO₂
  • CI₂ > SO₂ > CO₂ > NH₃
  • NH₃ > CO₂ > CI₂ > SO₂
  • NH₃ > CO₂ > SO₂ > CI₂
    correct

13. This is a known fact that the molar volumes of different gases at S.T.P. are

  • About the same as the molar volumes of liquids
  • Much larger than the molar volumes of liquids and solids
    correct
  • Little bit less than the molar volumes of solids
  • Little bit grater than the molar volumes of liquids

14. Imagine a man is sitting in a room. The room is closed from all sides, no entry, no exit of any gas. If the room expand suddenly then

  • His blood pressure will decrease
  • He will feel warmth
  • He will be frightened
  • He will feel cool
    correct

15. A real gas obeying Van der Wall’s equation will resemble ideal gas if the:

  • Both a and b are small
    correct
  • a is small and b is large a
  • a is large and b is small
  • Both a and b are large

Entry Test 2021 Chemistry Gases MCQS Online Preparation Sample Paper 2 Questions with Answer

1. What method is used to remove insoluble solids from muddy water?

  • Filtration
    correct
  • Evaporation
  • Distillation
  • Chlorination

2. The top of funnel stem should touch the side of the beaker because

  • The filtrate is quick
  • This gives bigger size crystals
  • Filtrate runs down without crystals
  • This gives medium size crystals
    correct

3. Fluted filter paper is used for

  • Increasing the rate of filtration
  • Filtering the hot saturated solution
    correct
  • To avoid premature crystallization of the solute
  • To dissolve large amount of substance at its boiling point

4. The solvent is selected for crystallization of a substance on the basis of:

  • On hit and trial basis
    correct
  • It should react chemically
  • Its polar nature
  • It non-polar nature

5. A bottle of copper (II) oxide has been contaminated wit5h some solid, NaCI. How can NaCI be removed from the (II) oxide?

  • Heat the mixture and allow it to cool
  • Add water to the mixture and filter
    correct
  • Add dilute acid to the mixture and filter
  • Place the mixture in a separating funnel

6. Solvent extraction method is particularly useful technique for separation when the product to be separated is:

  • Volatile or thermally stable
  • Volatile or thermally unstable
    correct
  • Non- volatile or thermally stable
  • Non –volatile or thermally unstable

7. A flask contains the liquids trichloromethane (chloroform) and H₂O They are separated using a separating funnel. Which conclusion can be made form this observation alone?

  • Trichloromethane and water do not mix
    correct
  • Trichloromethane and water having different boiling points
  • Trichloromethane and water have different relative masses
  • Trichloromethane has a higher density than water

8. Preparation of aspirin is carried out by the reaction of salicylic acid with

  • Acetic acid and ethyl alcohol
  • Acetic acid and acetic anhydride
    correct
  • Acetic acid and water
  • Acetic acid and sulphuric acid

9. From which mixture can the fast substance be obtained by adding water stirring and filtering?

  • Magnesium and iron
  • Sodium chloride and coppercorrect
  • Oxygen and nitrogen
  • sulphate

10. For smooth filtration one of the following precautions should be observed

  • The stem of the funnel should remain continuously full of liquids
  • The filter paper should be small
  • The tip of funnel should not touch the beaker
  • The stem of the funnel should be smallcorrect

11. Sublimation is a process for the separation of:

  • Solution of volatile and non-volatile liquids
  • Solute and solvent from a solution
  • Ionic and covalent compound
  • Volatile and non-volatile solidscorrect

12. Slow cooling of hot saturated solution yields.

  • Medium size crystal
  • Large size crystals
    correct
  • Premature crystallization of the solute
  • Immiscible liquids

13. Gooch crucible is used in a suction filtering apparatus, because:

  • It is used to separate organic compound from water
  • It keeps the stem of funnel full of liquid
  • It is used for filtration of precipitates which need to be in ignited
    correct
  • A solid compound is purified

14. The process of filtration is used to:

  • Separate the two immiscible liquids
  • Separate the two miscible liquids
  • Separate solute from solution
  • Separate insoluble particles from liquidscorrect

15. A filtration process could be very time consuming if it was not added by a gentle suction which is developed

  • If the stem of the funnel is large so that it dips into the filtrate
  • If the paper has got small size pores in it
  • If the paper covers the funnel up to its circumference
    correct
  • If the paper fits tightly

Entry Test 2021 Chemistry Gases MCQS Online Preparation Sample Paper 3 Questions with Answer

1. By increasing temperature the transition from a gas to an ionized gas gives free electrons called

  • Gas phase
  • Vapour density
  • UV radiation
  • Plasmacorrect

2. Which one is not postulated in the kinetic molecular theory among the followings?

  • Molecules of all the gases have same size and same masscorrect
  • All molecular collisions are elastic
  • The volume of the molecules is negligible
  • Molecules are in chaotic motion

3. All of the following statements are incorrect expect

  • Gas molecules do not attract each other at very low temperature
  • Actual volume of a gas in not negligible at very pressurecorrect
  • Increase of pressure will not decrease the inter molecular distance in a gas
  • All of the gases cannot be liquefied

4. A gas has non-ideal behavior at:

  • High temperature and high pressure
  • Low temperature and low pressure
  • High temperature and low pressure
    correct
  • Low temperature and high pressure

5. A teacher told his student that air is a mixture. This is due to the reason that suddenly a student raised his hand and said

  • Oxygen can be removed from it
  • It is colourless
  • Its composition is different at different altitudescorrect
  • It has different properties from its constituents

6. A pressure of 1Nm¯² is equal to:

  • One atmosphere
  • One pascal
    correct
  • Stalagmometer
  • One bar

7. Which of the following laws study the pressure-volume relationship of a gas at constant temperature?

  • Boyle’s law
    correct
  • Dalton’s law
  • Grahm’s law
  • Charle’s law

8. Consider the physical properties of the gases. Which of the following statements about particles of gases is incorrect? The particles are

  • Randomly moving
  • Causing pressure
  • Orderly arranged
    correct
  • Having wide spaces

9. If pressure is increased from 2 atm to 4 atm on a gas then its volume will decrease from:

  • 6L to 4L
  • 8L to 2L
  • 3L to 1L
  • 4L to 2L
    correct

10. To measure the true pressure of a gas collected over water, the pressure due to water vapors is?

  • Added to the total pressure
  • Subtracted from the total pressurecorrect
  • Divided by the total pressure
  • Multiplied to the total pressure

11. A room is closed from all side in which a person is sitting. There is no entry and no exit of any gas. If a room expands suddenly then.

  • He will feel cool
    correct
  • He will be frightened
  • His blood pressure will decrease
  • He will feel warmth

12. At constant temperature, volume of given mass of gas is inversely proportional to pressure on it. This statement is according to

  • Graham’s law
  • Hook’s law
  • Boyle’s law
    correct
  • Charle’s law

13. Suppose that all the air of the earth were replaced by an ocean of mercury. How deep would this ocean have to be to exert the same pressure as the air

  • 77cm
  • 76cm
    correct
  • 79cm
  • 78cm

14. Gases deviate from ideal behavior at high pressure. Which of the following is correct for non-ideality?

  • At high pressure, the gas molecules move in one direction only
  • At high pressure, the collisions between the gas molecules are increased manifold
  • A high pressure, the volume of the gas becomes insignificant
  • At high pressure, the intermolecular attraction becomes significantcorrect

15. The gases suddenly ______ if these are allowed to expand

  • Heat up
  • Cool down
    correct
  • React
  • Move randomly

Understanding chemistry gases and their behavior is essential for ECAT entry test preparation. The fundamental gas laws provide insights into real-world applications, from air pressure changes to industrial gas storage. By practicing MCQs, students can solidify their understanding and enhance their problem-solving skills for chemistry exams.

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