Tag: chemistry

Questions Related to chemistry

Which one of the following substance possesses the highest elasticity?

chemistry substances in the surroundings - their states and properties elastic behaviour of solids elastic and plastic substances properties of substances

  1. rubber

  2. glass

  3. steel

  4. copper

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Correct Option: C
Explanation:

Modulus of elasticity gives the idea of elasticity. For above materials, values of E are:
Glass: $50-90 GPa$
Rubber:$ 0.01-0.1 GPa$
Steel:$ 200 GPa$
Copper: $117 GPa$

Pick up the correct statement:

chemistry substances in the surroundings - their states and properties elastic behaviour of solids elastic and plastic substances properties of substances

  1. Cubic crystals exhibit isotropic nature with respect to therma expansion

  2. Anisotropic solids expand in one direction and contract in perpendicular direction

  3. Many of the crystals are anisotropic solids

  4. Rock salt crystal exhibits isotropic nature with respect to thermal expansion

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Correct Option: C

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. $5.53\ amu$

Show answer
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