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Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

One mole of any substance contains $6.022\times 10^{23}$ atoms/molecules. Number of molecules of $H 2SO _4$ present in $100$mL of $0.02$M $H _2SO _4$ solution is _________?

  1. $12.044\times 10^{20}$ molecules
  2. $6.022\times 10^{23}$ molecules
  3. $1\times 10^{23}$ molecules
  4. $12.044\times 10^{23}$ molecules
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Moles of $H _2SO _4=$ Molarity of $H _2SO _4\times $ Volume of solution $(L)$


$=0.02\times 0.1$


$=2\times 10^{-3}$ moles

No. of $H _2SO _4$ molecules $=2\times 10^{-3}\times 6.022\times 10^{23}=12.044\times 10^{20}$ molecules


Therefore, the correct option is A.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

Cations absorb $6.023\times 10^{22}$ electrons for their reduction. How many equivalents of the ion are reduced?

  1. $0.1$
  2. $0.01$
  3. $0.001$
  4. $0.0001$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

1 equivalent of ion absorbs 6. 023 $\times 10^{23}$ electrons 

No. of equivalents reduced = $\dfrac{6.023\times 10^{22}}{6.023 \times  10^{23}}$= 0.1

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

The number of gram molecule of oxygen in $6.02 \times 10^{24}$ CO molecules is :

  1. 10 gm molecules

  2. 5 gm molecules

  3. 1 gm molecules

  4. 0.5 gm molecules
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given :


$6.02\times 10^{24}$ $CO$ molecules


We know,

$1$ mole $CO$ equivalent to $6.023\times 10^{23}$ molecules of $CO$

$6.023\times 10^{23}$ molecules of $CO$ contain $6.023\times 10^{23}$ atoms of $O$

Then, $6.02\times 10^{24}$ $CO$ molecules contain $6.02\times 10^{24}$ atoms of $O$

$\Rightarrow$ no. of gram atoms of $O=\cfrac {6.02\times 10^{24}}{6.02\times 10^{23}}$

$=10gm$ atoms  $\longrightarrow 1$

As oxygen is a diatomic molecule.

No. of gm of molecules of oxygen=$\cfrac {10gm\quad atoms}{2\quad atoms/molecule}=5gm$ molecules

Therefore, the correct option is B.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

The number of g-atom of oxygen in $6.02\times { 10 }^{ 24 }$ $CO$ molecule is

  1. $1$
  2. $0.5$
  3. $5$
  4. $10$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

One molecule of $CO$ contains one oxygen atom
$\therefore 6.02\times { 10 }^{ 24 }\quad $ molecules of $CO$ contain $6.02\times { 10 }^{ 24 }$ oxygen atoms
$6.02\times { 10 }^{ 23 }$ atoms of oxygen $\equiv$ $1g$ atom of oxygen
$\therefore 6.02\times { 10 }^{ 24 }$ atoms of oxygen $\equiv$ $10g$ atom of oxygen.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

At room temperature and pressure, two flasks of equal volumes are filled with $H _2$ and $SO _2$ separately. Particles which are equal in number, in the two flasks are:

  1. atoms

  2. electrons

  3. molecules

  4. neutrons
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At a given volume at constant temperature and pressure, two gases have equal no. of moles 

hence, the no. of molecules will be same in both flasks.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

Which of the following statement about Avogadro's hypothesis is correct?

  1. Under similar conditions of temperature and pressure, gases react with each other in simple ratio.

  2. Under similar conditions of temperature and pressure, equal volumes of all gases contain same number of molecules

  3. At NTP all gases contain same number of molecules

  4. Gases always react with gases only at the given temperature and pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Avogadro’s Law states that under same conditions of temperature and pressure, equal volume of all the gases contain equal number of molecules.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

The molecular weights of $O _2$ and $N _2$ are $32$ and $28$ respectively. At $15^0$C, the pressure of $1$gm $O _2$ will be the same as that of $1$ gm $N _2$ in the same bottle at the temperature:

  1. $-21^0$C
  2. $-13^0$C
  3. $15^0$C
  4. $56.4^0$V
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Temperature of $O _{2}$ $=273+15=298 K$

Temperature of $N _{2}$ $=x$

As $n$ $\propto$ $\dfrac 1T$, as pressure is constant.

$\Longrightarrow { n } _{ 1 }{ T } _{ 1 }={ n } _{ 2 }{ T } _{ 2 }\Longrightarrow \left( \cfrac { 1 }{ 32 }  \right) \left( 298 \right) =\left( \cfrac { 1 }{ 28 }  \right) \left( x \right) \\ \Longrightarrow x=\cfrac { 28 }{ 32 } \times 298=260.75K$

Temperature in $^oC=260.75-273=-13 ^oC$

Hence, option $B$ is correct.
Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

Gram molar volume for a gas is always considered at ___ conditions.

  1. NTP

  2. STP

  3. variable temperature

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since volume is a dependent variable and it depends on pressure and temperature always so temperature and pressure should be specified when volume of gas is considered. For this certain standard conditions are taken as 273 K and 1 atm pressure.
And at STP, molar volume is 22.4 litre.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

Two gases A and B are taken in same volume containers under similar conditions of temperature and pressure. In container A, there are '2N' molecules of gas A. The number molecules does container B have :

  1. N

  2. 0.5N

  3. 2N

  4. 4N
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
1. According to Avogadro's law, the equal volume of gases under a similar condition of pressure and temperature contain equal no. of molecules. 
Therefore the number of molecules in container B will also be 2N.

2. As we know, one mole of each gas occupies 22.4-litre volume and one mole of gas contains NA molecules at STP.

So at the same temperature and pressure, the equal volume of gas contains equal no of molecules.

Therefore the number of molecules in container B will also be 2N.

Therefore, the option is C.