Tag: chemistry

Questions Related to chemistry

Gaseous mixture can be effectively separated by :

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

  1. distillation

  2. centrifugation

  3. synthetic membranes

  4. separation funnel

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Correct Option: C
Explanation:

Gas mixtures can be effectively separated by synthetic membranes made from polymers such as polyamide or cellulose acetate, or from ceramic materials.

$\displaystyle { CO } _{ 2 }$ and $\displaystyle CO$ can be separated by :

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

  1. Chromatography

  2. Solvent extraction

  3. Separation funnel

  4. Magnetic separation

Show answer
Correct Option: B
Explanation:

 A gaseous mixture containing CO$ _2$ and CO can be separated by solvent extraction.
The mixture is passed through water.  CO$ _2$ dissolves in water whereas CO does not.

In a mixture of $NH 3$NH3 and $H _2$, _____ Gets liquified under pressure :

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

  1. $\displaystyle { H } _{ 2 }$

  2. $\displaystyle { NH } _{ 3 }$

  3. $\displaystyle { H } _{ 2 }O$

  4. All of above

Show answer
Correct Option: B
Explanation:

In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under pressure
Liquefaction of gases is the process by which a gas is converted to a liquid. In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under high pressure and H$ _2$ is left behind.
Note: NH$ _3$ has a higher value of the van der Waal's constant 'a' than $H _{2}$
Hence, NH$ _3$ is more easily liquefiable than H$ _2$.

______ is useful when one gas is easily liquefiable.

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

  1. Solvent extraction

  2. Crystallisation

  3. Liquefaction

  4. All of the above

Show answer
Correct Option: C
Explanation:

Liquefaction is useful when one gas is easily liquefiable.
Liquefaction of gases is the process by which a gas is converted to a liquid by applying high pressure and low temperature. For example, oxygen normally occurs as a gas. However, by applying high pressure and by reducing the temperature, oxygen can be converted to a liquid.
Note:
In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under pressure
Liquefaction of gases is the process by which a gas is converted to a liquid. In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under high pressure and H$ _2$ is left behind.
NH$ _3$ has higher value of the van der Waal's constant 'a' than
Hence, NH$ _3$ is more easily liquefiable than H$ _2$.

Which of the following gases is heavier than air?

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

  1. Nitrogen

  2. Carbon monoxide

  3. Ammonia

  4. Sulphur dioxide

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Correct Option: D
Explanation:

Vapour Density for Sulphur dioxide is 32, for Nitrogen is 14, Carbon monoxide is 14 and ammonia is 8.5 .

Which of the following gases is lighter than air?

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

  1. Oxygen

  2. Hydrogen Chloride

  3. Ammonia

  4. Chlorine

Show answer
Correct Option: C
Explanation:

Vapour density for ammonia is 8.5 while for chlorine is 35.5, HCl is 18.25 and oxygen is 16.

Which of the following cannot be used for liquid-liquid separation?

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

  1. Magnet

  2. Sublimation

  3. Crystallization

  4. All of above

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Correct Option: D
Explanation:

Magnetic separation and sublimation can be used to separate solid from solid. Crystallization is used to recover solid from liquid. Hence, none of the above methods is used for separation of liquid from liquid.

Gaseous diffusion works on the principle that

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

  1. Molecules of a lighter isotope would pass through a porous barrier more readily than those of a heavier isotope

  2. Molecules of a heavier isotope would pass through a porous barrier more readily than those of a lighter isotope

  3. Heavier and lighter particles will pass readily through the porous barrier

  4. None of above

Show answer
Correct Option: A
Explanation:

Gaseous diffusion works on the principle that molecules of a lighter isotope would pass through a porous barrier more readily than those of a heavier isotope.

______for the removal of VOCs from air, in recent times have become important due to environmental and economic driving forces.

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

  1. Liqueafaction

  2. Condensation based gas separations

  3. Solubility-based gas separations

  4. Solidification

Show answer
Correct Option: C
Explanation:

Solubility-based gas separations for applications such as the removal of VOCs from air, in recent times have become important due to environmental and economic driving forces.The main objective is to obtain membranes that exhibit high permeability and high selectivity for the heavier species over the light gases.

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?

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

  1. $21$mL $O _2$

  2. $3.0$mL $H _2$

  3. $24$mL $O _2$

  4. $28$mL $O _2$

Show answer
Correct Option: A
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.