Tag: atoms and molecules

Questions Related to atoms and molecules

Which of the following molecules specie has the minimum number of lone pairs ? 

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $ X _eF _4 $

  2. $ BF^- _4 $

  3. $ ICI _3 $

  4. $ BeF _2 $

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Correct Option: D

A quantity of $2.0\ g$ of a triatomic gaseous element was found to occupy a volume of $448\ ml$ at $76\ cm$ of $Hg$ and $273\ K$.

The mass of its each atom is _______________.

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $100\ amu$

  2. $5.53\times 10^{-23}\ g$

  3. $33.3\ g$

  4. $5.53\ amu$

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Correct Option: B
Explanation:
Given that
$P=76\ cm$ of $Hg =1\ atm$
$V=448\ ml=0.448\ L$
$T=273\ K$

Now,
$PV=nRT$

$n=\dfrac{PV}{RT}=\dfrac{1\times 0.448}{0.082\times 273}=0.02\ moles$

No. of moles $=\dfrac{mass}{molar\ mass}$

Molar mass $=\dfrac{mass}{mole}$

$3\times$ atomic mass $=\dfrac{2}{0.02}$

Atomic mass $=33.3\ g$

$\therefore$ mass of $1\ atom=\dfrac{33.3}{6.022\times 10^{23}}=5.53\times 10^{-23}\ g$

Which of the following gas molecule has the longest mean free path at the same pressure and temperature?

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $H _2$

  2. $N _2$

  3. $O _2$

  4. $Cl _2$

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Correct Option: A

Two gases X and Y have their molecular speed in ratio of $3:1$ at certain temperature. The ratio of their molecular masses $M _x:M _y$ is?

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $1:3$

  2. $3:1$

  3. $1:9$

  4. $9:1$

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Correct Option: C

The waste of nuclear power plant contains $C^{12}$ and $C^{14}$ in ratio of $4:1$ by moles. What is the molecular mass of methane gas produced from this disposed of $C^{12}$ and $C^{14}$ are $98\%$ and $2\%$, respectively. 

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $15.998$

  2. $16.0053$

  3. $16$

  4. $16.4$

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Correct Option: A

A gaseous mixture of three gases A, B and C has a pressure of $10$ atm. The total number of moles of all the gases is $10$. If the partial pressures of A and B are $3.0$ and $1.0$ atm, respectively, and if C has molecular mass of $2.0$, what is the mass of C, in g, present in the mixture?

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $6$

  2. $8$

  3. $12$

  4. $3$

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Correct Option: A

Which of the following will have the composition (by mass) mass similar as that of acetic acid?

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. Methyl formate, $HCOOCH _{3}$

  2. Glucose, $C _{6}H _{12}O _{6}$

  3. Formaldehyde, $HCHO$

  4. Formic acid, $HCOOH$

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Correct Option: A,B,C

A quantity of $5.0$g of a mixture of He and another gas occupies a volume of $1.5$l at $300$K and $750$mm Hg. The gas freezes at $270$K. At $15$K, the pressure of the gas mixture is $8$mm Hg(at the same volume). What is the molecular mass of the gas?

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $103.8$

  2. $4.0$

  3. $495$

  4. $82.24$

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Correct Option: A

A protein, isolated from a bovine preparation, was subjected to amino acid analysis. The amino acid present in the smallest amount was lysine, $C _6H _{14}N _2O _2$ and the amount of lysine was found to be $365\ mg$ per $100\ g$ protein. What is the minimum molecular mass of the protein?   

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $40,000,000$

  2. $40, 000$

  3. $40$

  4. $4, 00,000$

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Correct Option: A

A mixture contains $NaCl$ and unknown chloride $MCl$. When $1\ g$ of this mixture is dissolved in water and excess of $AgNO _{3}$ Solution is added to it, $2.567\ g$ of white precipitate is obtained. In another experiment, $1\ g$ of the same original mixture is heated to $300^{o}C$. Some vapour come out which are absorbed in acidified $AgNO _{3}$ solution by which $1.341\ g$ of white precipitate is formed. The molecular mass of unknown chloride is

introduction to mole gas laws and mole concept atoms and molecules chemistry mole concept chemical formula and mole concept

  1. $53.4$

  2. $58.5$

  3. $44.5$

  4. $74.4$

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Correct Option: A,B