Tag: chemistry

Questions Related to chemistry

If a steam-jacket eudiometer with 23ml of oxygen and 4ml of hydrogen are mixed over mercury, determine the total volume in ml of the gas after the mixture was sparked?

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

  1. $16$

  2. $25$

  3. $34$

  4. $36$

  5. $40$

Show answer
Correct Option: B
Explanation:

$\displaystyle  2H _2 + O _2 \rightarrow 2H _2O$
2 moles of hydrogen will react with 1 mole of oxygen to form 2 moles of water.
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 to form 4 ml of water.
$\displaystyle  23-2 = 21 ml$  of oxygen will be left uncombined.
Thus, after the mixture was sparked, 21 ml oxygen and 4 ml water are present.
Total volume of the gas after the mixture was sparked $\displaystyle  = 21 + 4 = 25 $ ml.

_______is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride through semipermeable membranes.

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

  1. Gas solubility

  2. Gas condensation

  3. Solidification

  4. Gas diffusion

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Correct Option: D
Explanation:

Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 and uranium-238. By use of a large cascade of many stages, high separations can be achieved. 

A technique in which two liquids are separated by heating process is known as :

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

  1. distillation

  2. filtration

  3. evaporation

  4. sublimation

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Correct Option: A
Explanation:

Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture.

A cheque was suspected to be forged. Which technique could be used to compare the various pigments in the different inks?

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

  1. Chromatography

  2. Evaporation

  3. Crystallisation

  4. Sublimation

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Correct Option: A
Explanation:

A cheque was suspected to be forged. Chromatography could be used to compare the various pigments in the different inks.  Here, different inks will have different affinity for  stationary phase  and solvent (mobile phase).

Fractional distillation is used to obtain the components of which of the following?
I air
II seawater
III muddy water
IV crude oil 

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

  1. I, II

  2. II, III

  3. I, IV

  4. I, III

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Correct Option: C
Explanation:

Fraction distillation is based upon the separation of components having very less boiling point difference, therefore components of crude oil and air can be separated using fractional distillation. In the air and in crude oil, the difference in boiling point of different components is very less. 

The vapour pressure of pure $A$ is $10$ torr and at the same temperature when $1\ g$ of $B$ is dissolved in $20\ g$ of $A$, its vapour pressure is reduced to $9.0$ torr. If the molecular mass of $A$ is $200\ amu$, then the molecular mass of $B$ is:

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

  1. $100\ amu$

  2. $90\ amu$

  3. $75\ amu$

  4. $120\ amu$

Show answer
Correct Option: B
Explanation:

So $0.1=\dfrac{moles \,\, of \,\, B}{moles of A+B}$

$0.1=\dfrac{1/m^2}{\dfrac{1}{m _2}+\dfrac{20}{200}}$
$0.1=\dfrac{1/m _2}{\dfrac{1}{m _2}+0.1}$
$\dfrac{0.1}{m _2}+0.01=\dfrac{1}{m _2}-\dfrac{0.1}{m _2}$
$0.01=\dfrac{0.9}{m _2}$
$m _2=\dfrac{0.9}{0.01}=90amu$

Which of the following technique is used for the separation of a mixture of a liquid and a gas?

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

  1. Boiling

  2. Sublimation

  3. Crystallization

  4. Fractional distillation

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Correct Option: A
Explanation:

The technique used for the separation of a mixture of a liquid and a gas is boiling. The gas is removed by application of heat.  With the increase in temperature, the solubility of gas decreases. The gas is collected separately

A mixture of hydrogen and chlorine can be seperated by passage through a porous pot.

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

  1. True

  2. False

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Correct Option: A
Explanation:

A mixture of hydrogen and chlorine can be separated by passage through a porous pot. This is because the diffusion of hydrogen more than that of chlorine in the porous pot. So, most of chlorine remains outside the pot.

${K} _{H}$ values for ${Ar} _{(g)}, {CO} _{2(g)}, {HCHO} _{(g)}$ and ${CH} _{4(g)}$ are $40.39,1.67,1.83\times {10}^{-5}$ and $0.413$ respectively. Arrange these gases in the order of their increasing solubility ?

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

  1. $HCHO< {CH} _{4}< {CO} _{2}< Ar$

  2. $HCHO< {CO} _{2}< {CH} _{4}< Ar$

  3. $Ar< {CO} _{2}< {CH} _{4}< HCHO$

  4. $Ar< {CH} _{4}< {CO} _{2}< HCHO$

Show answer
Correct Option: C
Explanation:

The solubility of the gas is inversely proportiona to the $K _H$ value. Here, $Ar$ gas has the highest $K _H$ value so least solubility and $HCHO$ gas has the least $K _H$ value so highest solubility.


So, the correct option is C.

Alcohol and water are best separated from one another by :

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

  1. distillation

  2. crystallization

  3. manual separation

  4. chromatography

  5. filtration

Show answer
Correct Option: A
Explanation:

Alcohol and water are best separated from one another by distillation. 


Alcohol and water are miscible but they have different boiling points.

If the difference in the boiling points of alcohol and water is less, fractional distillation can be used.

Hence the correct option is A.