Matter and Separation of mixture Questions in English

(B) $Heterogeneous$ mixture can be separated into its constituents by physical methods such as filtration,crystallization,and distillation.
In a $Heterogeneous$ mixture,the composition is not uniform throughout,and the components can often be physically distinguished,allowing for separation based on differences in physical properties like particle size,solubility,or boiling point.

(A) The atomic theory of matter was first proposed by the school teacher $John \ Dalton$ in $1808$ based on scientific evidence.
It suggests that atoms are the ultimate,indivisible particles of matter.

(B) Physical properties of ice,water and steam differ because they exist in different physical states.
Ice is the solid state,water is the liquid state,and steam is the gaseous (vapour) state.
However,the chemical composition of water in all three states remains the same,which is $H_2O$.

(N/A) Definition: Macroscopic properties of matter are those properties that are associated with a large number of atoms,ions,or molecules.
Examples: $(i)$ An individual molecule of a liquid does not boil,but a bulk of it does. $(ii)$ An individual molecule of water does not wet a surface,but a bulk of it does.

(A) In vapour distillation (specifically steam distillation),the mixture obtained consists of two immiscible layers: water and the organic liquid. Since they are immiscible,they can be easily separated using a $separating \text{ } funnel$.

(A) The principle of distillation is based on the difference in the boiling points of the components of a liquid mixture.
Every pure liquid has a definite boiling point at a given pressure.
When a mixture is heated,the component with the lower boiling point vaporizes first,and these vapors are then condensed back into a liquid to be collected separately.

(N/A) $(i)$ Dissolve the mixture in water,filter to remove sand,and then concentrate the filtrate to obtain sugar crystals through crystallization.
$(ii)$ Use a separating funnel to separate the immiscible layers of kerosene and water.
$(iii)$ Benzene can be separated from common salt by distillation.
$(iv)$ Fractional distillation is used for liquids with close boiling points.
$(v)$ Sublimation is the preferred technique as camphor sublimes while aniline does not.

(A) The liquid $(A)$ with the lower boiling point comes out first in the distillate.
Fractional distillation is used to separate the components of a mixture if their boiling points differ by $20^{\circ}C$ or less. In this method,a fractionating column is used between the flask and the condenser. The purpose of the fractionating column is to provide hurdles for the ascending vapours and to provide a large surface area for condensing the high-boiling liquid.
As a result,the vapours of the low-boiling liquid $(A)$ will move up,while those of the high-boiling liquid $(B)$ will condense and flow back into the flask.
Therefore,in this method,liquid $(A)$ with the lower boiling point will distil first,and liquid $(B)$ with the higher boiling point will distil afterwards.

(N/A) The order of boiling points is $A \gg C > B$.
The boiling point of liquid $A$ is much higher than those of liquids $B$ and $C$,whose boiling points are quite close. Therefore,we can separate the mixture of $B$ and $C$ from $A$ by simple distillation.
During distillation,the mixture of $B$ and $C$ will distill together at a lower temperature,leaving behind liquid $A$ in the flask. On further heating,liquid $A$ will distill separately. The components $B$ and $C$ can then be separated from each other using fractional distillation,as their boiling points are close.

(N/A) If the difference in boiling points of two liquids is small,the fractional distillation method is used.
The vapour of the liquid mixture condenses before it passes through the column. This distillation column is arranged with a round-bottom flask as shown in the figure.
If the difference in boiling point is very small,a bubble plate type fractionating column is used as shown in the figure.
In a bubble plate column,the tower is divided into a number of compartments by means of shelves having openings. The openings are covered with caps called bubble caps.
Each shelf is provided with an overflow pipe which keeps the liquid at a certain level and allows the rest to trickle down to the lower shelf.
Such a type of column is used for continuous separation of bulk quantities of liquids. For example,distillation of fermented liquid for the manufacture of rectified spirit.
Industrial applications:
$(i)$ Separation of crude oil in the petroleum industry into various useful fractions such as gasoline,kerosene oil,diesel oil,lubricating oil,etc.
$(ii)$ Separation of water and methanol from pyroligneous acid obtained by destructive distillation of wood.

(D) Statement $I :$ The boiling point $(B.P.)$ of chloroform is $334 \ K$ and the $B.P.$ of aniline is $457 \ K$. Since there is a large difference in their boiling points,they can be separated by simple distillation. Thus,Statement $I$ is true.
Statement $II :$ In steam distillation,the mixture boils at a temperature lower than the boiling point of either component. Aniline is steam volatile and is separated from water by this method,where it boils at a temperature lower than its normal $B.P.$ of $457 \ K$. Thus,Statement $II$ is true.

(D) Benzoic acid is soluble in hot water,while naphthalene is insoluble in water. Therefore,they can be separated by crystallization using hot water,not benzene.
Assertion $A$ is false because benzene would dissolve both benzoic acid and naphthalene,making separation difficult.
Reason $R$ is true as benzoic acid is indeed soluble in hot water.
Thus,$A$ is false but $R$ is true.

(D) The $R_{f}$ value is defined as the ratio of the distance travelled by the substance to the distance travelled by the solvent front.
$R_{f(A)} = \frac{2.08}{3.25}$
$R_{f(B)} = \frac{1.05}{3.25}$
The ratio of $R_{f}$ values of $A$ to $B$ is $\frac{R_{f(A)}}{R_{f(B)}} = \frac{2.08 / 3.25}{1.05 / 3.25} = \frac{2.08}{1.05} \approx 1.98 \approx 2$.

(C)
$A$ mixture of $NH_4Cl$ and $NaCl$ can be separated by the process of sublimation.
In this process,a solid directly changes to a gaseous state without passing into the liquid state.
$NH_4Cl$ sublimes upon heating,whereas $NaCl$ does not sublime.
The reaction can be written as:
$NH_4Cl_{(s)} \longrightarrow NH_{3(g)} + HCl_{(g)}$

(C) The separation of $Acetone$ and $Benzene$ from their mixture is effectively carried out by $Fractional \ distillation$ using a $fractionating \ column$.
This method is employed because the boiling points of $Acetone$ $(56 \ ^\circ C)$ and $Benzene$ $(80 \ ^\circ C)$ are relatively close,necessitating the use of a fractionating column to achieve efficient separation through repeated vaporization and condensation cycles.

(A) The correct method is $sublimation$.
$Ammonium \ chloride$ $(NH_4Cl)$ is a sublime substance,meaning it changes directly from a solid to a gas upon heating.
$Sodium \ chloride$ $(NaCl)$ does not sublime.
Therefore,when the mixture is heated,$NH_4Cl$ vaporizes and can be collected,leaving $NaCl$ behind.

(A) mixture of iodine $(I_2)$ and sodium sulphate $(Na_2SO_4)$ is separated by the process of sublimation.
Sublimation is the transition of a substance directly from the solid phase to the gas phase without passing through the liquid state.
In this mixture,iodine acts as a sublimate (a volatile component),while sodium sulphate is a non-sublimable impurity.
Upon heating,iodine vaporizes,leaving behind the solid sodium sulphate,allowing for their effective separation.

(D) homogeneous mixture is a mixture in which the composition is uniform throughout the mixture.
$Ethyl \ alcohol$ and $water$ are polar in nature and can form hydrogen bonds with each other,making them miscible in all proportions.
Therefore,the $(Ethyl \ alcohol + Water)$ system forms a homogeneous mixture.

(C) According to John Dalton's atomic theory,he proposed specific symbols for various elements. The symbol for hydrogen was represented as a circle with a dot in the center $(\odot)$. However,looking at the provided options and the standard historical representation,the symbol $\odot$ is the correct representation for hydrogen in Dalton's notation.

(C) The reaction $C_{(graphite)} \longrightarrow C_{(g)}$ represents the conversion of a solid substance (graphite) directly into its gaseous state.
This process of phase transition from solid to gas is known as sublimation.
Therefore,the correct process is sublimation.

(B) miscible mixture of $C_6H_6 + CHCl_3$ can be separated by distillation.
The boiling point of benzene $(C_6H_6)$ is $80^{\circ} C$ and that of chloroform $(CHCl_3)$ is $61.2^{\circ} C$.
Since there is a significant difference in their boiling points,the mixture can be separated by distillation,where the component with the lower boiling point $(CHCl_3)$ evaporates first and is collected separately.

(D) Homogeneous mixtures have uniform composition throughout. Thus,among the given options,a dilute aqueous solution of sugar is a homogeneous mixture and has a uniform composition.

(C) The separation of liquids into their pure form from a liquid mixture is achieved by the fractional distillation technique.
This technique is employed when the components of the mixture have a difference in their boiling points,typically in the range of $10-40 \ K$.

(D) Gasoline is a mixture of hydrocarbons,primarily $C_8H_{18}$,present in crude oil along with many other components.
Since these components have different boiling points,they are separated by the process of fractional distillation.
Hence,option $(D)$ is the correct answer.

(D) Statement-$I$ is false because sublimation is used for the separation and purification of compounds that sublime upon heating,not specifically those with low melting points.
Statement-$II$ is false because the boiling point of a liquid decreases as the external pressure is reduced,not increases.