Chemistry · Physics

Gases and Gas Laws

298 Questions

The study of gases and gas laws involves understanding the relationships between pressure, volume, and temperature of gases. This topic is essential for chemistry and physics sections in many competitive exams. Practice these questions to master concepts like the ideal gas law, partial pressure, and molecular properties.

Ideal gas law calculationsGas volume and pressureStoichiometry of gasesDensity of gasesBoltzmann constant applicationsThermal speed of sound

Gases and Gas Laws Questions

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Different proportions of oxygen in the various oxides of nitrogen prove the law of :

  1. equivalent proportion

  2. multiple proportion

  3. constant proportion

  4. conservation of matter
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Different proportions of oxygen in the various oxides of nitrogen prove the law of multiple proportions.
According to the law of multiple proportions,
 "if two elements chemically combine with each other forming two or more compounds with different compositions
by mass then the ratios of masses of two interacting elements in the two compounds are small whole numbers".

Example.
14 g of nitrogen combine with 16  g of oxygen to form 30 g of $NO$.
The ratio of masses $N:O$ is $14:16$.

14 g of nitrogen combine with 32  g of oxygen to form 46 g of $NO _2$.
The ratio of masses $N:O$ is $14:32$.

The two ratios are in the proportion of $32:16=2:1$.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Hydrogen and oxygen forms two compounds. The hydrogen content in these compounds is 42.9% and 27.3%. These compounds follow which law ?

  1. Law of definite proportion

  2. Law of reciprocal proportion

  3. Law of multiple proportion

  4. Law of combining volumes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The law of multiple proportions state that if two elements form more than one compound between them then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Which of the following statements illustrates the law of multiple proportions?

  1. An element forms two oxides, XO and $XO _2$ containing $50\%$ and $60\%$ oxygen respectively. The ratio of masses of oxygen which combines with 1 g of element is 2:3
  2. Hydrogen sulphide contains $5.89\%$ hydrogen, water contains $11.1\%$ hydrogen and sulphur dioxide contains $50\%$ oxygen.
  3. 3.47 g of $BaCl _2$ reacts with 2.36 g of $Na _2SO _4$ to give 3.88 g of $BaSO _4$ and 1.95 g of NaCl.
  4. 20 mL of ammonia gives 10 volumes of $N _2$ and 30 volumes of $H _2$ at constant temperature and pressure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Law of multiple proportions states that when two elements combine to form two or more compounds, the masses of one element which combine with the fixed mass of another element, will always be in ratio of whole numbers.
The statement is :
An element forms two oxides $XO$ and ${ XO } _{ 2 }$ containing $50$% and $60$% of oxygen respectively. The ratio of masses of ${ O } _{ 2 }$ which combine with $1g$ of element of $2:3$.
Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Find the ratio of a systolic blood pressure of $120$ (in mm of Hg) to atmospheric pressure. Standard atmospheric pressure is $1.01\times 10^{5}\ Pa$

  1. 0.16

  2. 1.6

  3. 16

  4. 160
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Systolic pressure is 120 mm Hg. Convert this to Pascals: P = h * d * g = 0.12 m * 13600 kg/m^3 * 9.8 m/s^2 = 15993.6 Pa. The ratio to standard atmospheric pressure (1.01 * 10^5 Pa) is 15993.6 / 101000, which is approximately 0.158, rounding to 0.16.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

In a box with a semi-permeable membrane containing a mixture of two gases

  1. The heavier molecules will pass out of the container more rapidly than the lighter molecules

  2. The lighter molecules will pass out of the container more rapidly than the heavier molecules

  3. Both heavier and lighter pass out of the container at equal rates

  4. Both a and c
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a box with a semi-permeable membrane containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier molecules. The gas leaving the container is somewhat enriched in the lighter molecules, while the residual gas is somewhat depleted. 

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

In a box with a semi-permeable membrane containing a mixture of two gases, the _____________ will pass out of the container more rapidly.

  1. Lighter molecules

  2. Heavy molecules

  3. All molecules equally

  4. None of above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gaseous diffusion is based on Graham's law, which states that the rate of effusion of a gas is inversely proportional to the square root of its molecular mass. For example, in a box with a semipermeable membrane containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

If a steam-jacket eudiometer with $23ml$ of oxygen and $4ml$ of hydrogen are mixed over mercury, determine how much and which gas would be left as uncombined after the mixture is sparked?

  1. $21$mL $O _2$
  2. $3.0$mL $H _2$
  3. $24$mL $O _2$
  4. $28$mL $O _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\displaystyle  2H _2 + O _2 \rightarrow 2H _2O$
2 moles of hydrogen will react with 1 mole of oxygen.
Volume is directly proportional to the number of moles.
4 ml of hydrogen will react with $\displaystyle  \dfrac {4 \times 1}{2}= 2$  ml of oxygen.
$\displaystyle  23-2 = 21 ml$  of oxygen will be left uncombined.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

If a steam-jacket eudiometer with 23ml of oxygen and 4ml of hydrogen are mixed over mercury, determine the total volume in ml of the gas after the mixture was sparked?

  1. $16$
  2. $25$
  3. $34$
  4. $36$
  5. $40$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\displaystyle  2H _2 + O _2 \rightarrow 2H _2O$
2 moles of hydrogen will react with 1 mole of oxygen to form 2 moles of water.
Volume is directly proportional to the number of moles.
4 ml of hydrogen will react with $\displaystyle  \dfrac {4 \times 1}{2}= 2$  ml of oxygen to form 4 ml of water.
$\displaystyle  23-2 = 21 ml$  of oxygen will be left uncombined.
Thus, after the mixture was sparked, 21 ml oxygen and 4 ml water are present.
Total volume of the gas after the mixture was sparked $\displaystyle  = 21 + 4 = 25 $ ml.

Multiple choice various types of barometer fluids physics

A thin tube of uniform cross - section is sealed at both ends. It lies horizontally, the middle $5 \,cm$ containing mercury and the two equal ends containing air at the same pressure P. When the tube is held at an angle $60^o$ with the vertical, the lengths of the air column above and below the mercury are $46$ and $44.5$ cm respectively. Calculate the pressure P, in cm of Hg. (The temperature of the system is kept at $30$ K)

  1. $92.5$ cm of Hg
  2. $75.4$ cm of Hg
  3. $73.0$ cm of Hg
  4. $70.5$ cm of Hg
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using the ideal gas law PV=nRT and the condition that the mercury column is in equilibrium, the pressure P can be determined by balancing forces at the given angle. The change in air column lengths due to the shift in mercury position allows for solving the system of equations for P. The calculated value aligns with 75.4 cm of Hg.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

All samples of carbon dioxide contain carbon and oxygen in the mass ratio of $3 : 8$. This is in agreement with the law of :

  1. conservation of mass

  2. constant proportion

  3. multiple proportions

  4. gaseous volumes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

LAW OF CONSTANT OR DEFINITE PROPORTION : It was given by Proust.
It states that all chemical compounds are found to have constant composition irrespective of their method of preparation or sources.
THE LAW OF MULTIPLE PROPORTION : It was given by Dalton.
It states that when one element combines with the other element to form two or more different compounds, the mass of one element which combines with a constant mass of the other bear a simple ratio to one another.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions
Four different experiments were conducted in the following ways-

I) $3g$ of carbon was burnt in $8g$ of oxygen to give $11g$ of $CO _2$

II) $1.2g$ of carbon was burnt in air to give $4.2g$ of $CO _2$,

III) $4.5g$ of carbon was burnt in enough air to give $11g$ of $CO _2$

IV) $4g$ of carbon was burnt in oxygen to form $30.3g$ of $CO _2$


Law of constant proportions is illustrated in which of the following experiment(s)?

  1. I and III only

  2. II and III only

  3. IV only

  4. I only
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The law of constant proportions states that a chemical compound always contains its component elements in a fixed ratio by mass. Experiment I shows 3g C + 8g O2 = 11g CO2, a ratio of 3:8. Experiment III also shows 4.5g C + 6.5g O2 = 11g CO2, which is not 3:8, but the question asks for the experiment illustrating the law. Experiment I is the standard demonstration.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

A sample of pure carbon dioxide, irrespective of its source contains 27.27 % carbon and 72.73% oxygen. The given data supports: 

  1. Law of constant composition

  2. Law of conservation of mass

  3. Law of reciprocal proporties

  4. Law of multiple proportions
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of constant composition (or definite proportions) states that a chemical compound always contains the same elements in the same proportions by mass, regardless of the source.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

3 volumes of hydrogen are required to combine with one volume of nitrogen to form 2 volumes of ammonia. When 1 mole of hydrogen is allowed to react with the mole of nitrogen, the two gases?

  1. Do not combine

  2. Combine and both the gases are used up completely

  3. 2/3 mole of nitrogen remains unreacted

  4. Some hydrogen remains uncombined
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$3H _2+N _2\rightarrow 3NH _3$
So 3 moles of hydrogen produced 1 mole of ammonia
1 mole hydrogen produces $X$ moles of ammonia
$X=\dfrac{1\times 1}{3}=\dfrac{1}{3}$ moles
Hence option $C$ is correct.