Tag: avogadro law

Questions Related to avogadro law

Assertion : 20 gm of argon (atomic mass of Ar $=40)$ occupies volume of $22400\ cm^3$ at STP.
Reason : 20 gm of Neon (atomic mass of $Ne=20$) occupies a volume of $22400\ cm^3$ at STP.

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

  2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

  3. Assertion is correct but Reason is incorrect.

  4. Assertion is incorrect but Reason is correct.

  5. Both assertion and reason are incorrect.

Show answer
Correct Option: D
Explanation:

20 g of argon is 0.5 moles and it occupies $(0.5\times 22400=)11200\ cm^3$ at STP.
20 g of Neon is 1 mole and occupies a volume of $22400\ cm^3$ at STP.

Let 'p' be the initial pressure of a gas. If the volume of a given mass of the gas, at constant temperature, becomes three times, the pressure will be:

chemistry atoms and molecules avogadro hypothesis avogadro's law avogadro law

  1. 3p

  2. p/3

  3. 9p

  4. p

Show answer
Correct Option: B
Explanation:

According to Boyle's law,

$P _1V _1=P _2V _2$
$pV _1=P _2.3V _1$
$\Rightarrow P _2=p/3$

According to Avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain:

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. the same number of molecules

  2. different number of molecules

  3. the same number of molecules only if their molecular masses are equal

  4. the same number of molecules if their densities are equal.

Show answer
Correct Option: A
Explanation:

According to avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain, the same no. of molecules.

For eg. One volume of hydrogen combines with one volume of chlorine to produce two volumes of HCl gas.
$H _2\1vol$   $+$  $Cl _2=\1 vol$ $2HCl\2 vol$

Which of the following statements is the most accurate with regard to the significance of Avogadro's number, $6.02 \times 10^{23}$ ?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. It is the conversion factor between grams and atomic mass units.

  2. It is a universal physical constant just as the speed of light.

  3. It is the number of particles that is required to fill a $1\ L$ container.

  4. It is the inverse diameter of an $H$ atom .

Show answer
Correct Option: A
Explanation:

A carbon atom weighs 12 AMU, one AMU is equivalent to $1.66 \times 10^{-24}$ grams. Conversely, one gram is equivalent to $6.022 \times 10^{23}$ AMU, which is called Avogadro's number


so the answer is A

The volume occupied by half a mole of a gas at STP is:

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. 5.6 L

  2. 11.2 L

  3. 22.4 L

  4. 44.8 L

Show answer
Correct Option: B
Explanation:
The volume occupied by 1 mole of any gas is 22.4 litres.

So the volume occupied by half a mole of gas would be half of 22.4 litres.

So it will be $11.2\ litres$.

Hence, option B is correct.

At constant temperature, in a given mass of an ideal gas:

chemistry atoms and molecules avogadro hypothesis avogadro's law avogadro law

  1. the ratio of pressure and volume always remains constant

  2. volume always remains constant

  3. pressure always remains constant

  4. the product of pressure and volume always remains constant

Show answer
Correct Option: D
Explanation:

Boyle's Law states that, at constant temperature, the product of the pressure and volume of a given mass of an ideal gas in a closed system, is always constant.

The critical volume of a gas is 0.036 $lit. mol^{-1}$. The radius of the molecule will be (in cm):
(Avogadro Number = $6 \times 10^{23}$)

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. $\displaystyle \left( \frac{9}{4 \pi} \times 10^{-23} \right)^{\dfrac{1}{3}}$

  2. $\displaystyle \left( \frac{8 \pi}{3} \times 10^{-23} \right)^{\dfrac{1}{3}}$

  3. $\displaystyle \left( \frac{3}{8 \pi} \times 10^{-23} \right)^{\dfrac{1}{3}}$

  4. none of these

Show answer
Correct Option: C
Explanation:

Critical volume of gas=3b [for 1 molecule]

For 1 mole, critical volume=0.036 liters
$\Longrightarrow 0.036\times { 10 }^{ 3 }{ cm }^{ 3 }=3\left( \cfrac { 4 }{ 3 } \pi { r }^{ 3 } \right) \times { N } _{ A } \ \Longrightarrow r={ \left( \cfrac { 36 }{ 24\pi  } \times 10^{ -23 } \right)  }^{ \cfrac { 1 }{ 3 }  }={ \left( \cfrac { 3 }{ 8\pi  } \times 10^{ -23 } \right)  }^{ \cfrac { 1 }{ 3 }  }$

The mass of a molecule of the compound $C {60}H _{122}$ is _________.

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. $1.4\times 10^{-21}$ g

  2. $1.09\times 10^{-21}$ g

  3. $5.025\times 10^{23}$ g

  4. $16.023\times 10^{23}$ g

Show answer
Correct Option: A
Explanation:

Molecular mass of $C _{60}H _{122}=(60 \times 12+1 \times 122)=720+122=842$


Hence, one mole contains $6.022 \times 10^{23}$ molecules 


Therefore, 

Mass of one molecule $=\frac{842}{6.022 \times 10^{23}}$

$=1.4 \times 10^{-21}\;g$


The correct option is A.

If you are given Avogadro's number of atoms of a gas $X$. If half of the atoms are converted into $X _{(g)}^+$ by energy $\Delta H$. The IE of $X$ is :

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. $\dfrac{2\Delta H}{N _A}$

  2. $\dfrac{2N _A}{\Delta H}$

  3. $\dfrac{\Delta H}{2N _A}$

  4. $\dfrac{N _A}{\Delta H}$

Show answer
Correct Option: A
Explanation:
Given no. of atoms = Avogadro's no. of atoms = ${N} _{A} = 6.023 \times {10}^{23}$
Given that $\cfrac{{N} _{A}}{2}$ atoms are ionized, i.e.,
Ionization energy of $\cfrac{{N} _{A}}{2}$ atoms of gas X = $\Delta{H}$

$\therefore$ Ionization energy of 1 atom of gas X = $\cfrac{\Delta{H}}{\left( \cfrac{{N} _{A}}{2} \right)} = \cfrac{2. \Delta{H}}{{N} _{A}}$
Hence, Ionisation energy of gas X is $\cfrac{2. \Delta{H}}{{N} _{A}}$.

Assuming that the all volume is measured at the same temperature and pressure, state the volume ratios of the reactants and products for the following gaseous reactions. Nitrogen reacting with oxygen to form nitrogen (III) oxide.

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. 1 : 3 : 2

  2. 2 : 4 : 2

  3. 2 : 2: 1

  4. 2 : 3 : 2

Show answer
Correct Option: D
Explanation:

The equation for the reaction between nitrogen and oxygen to form Nitrogen (lll) oxide is written as:
$2N _{2} + 3O _{2} \rightarrow 2N _{2}O _{3}$
Therefore the volume ratio of reactants and products $= 2 : 3 : 2$