States of Matter Test

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States of Matter Test - 21

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Question 1
1 / -0

Just because you mix two things together does not necessarily mean they will form a homogeneous mixture (a solution). For example, if you add sodium chloride, $$NaCl$$, to a container that has both hexane and water, the $$NaCl$$ will dissolve into the water, but will not be found in the hexane $$C_{6}H_{14}$$.
Which of the following statement BEST explains these observations?

A
Polar water molecules form ion-dipole forces with the ions of $$NaCl$$. Hexane, being nonpolar, cannot form these ion-dipole interactions.

B
Nonpolar hexane molecules tend to repel the ions that make up $$NaCl$$.

C
Nonpolar hexane is less dense that water, so when the two are in the same container, any $$NaCl$$ that is added to the mixture sinks to the bottom of the container and cannot get into the hexane layer.

D
Nonpolar hexane molecules and water molecules repel one another.

Solution

Like dissolve like is a principle behind homogeneous mixing (i,e formation of solution). For example NaCl is ionic (polar) so it get dissolve in $$H_2O$$ (polar). but not in haxane (non-polar ) due to ion- dipole interaction between NaCl and $$H_2O$$.
Question 2
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Small insects such as the water strider can walk on water due to which phenomenon (Choose the best one)

A
viscosity

B
surface tension

C
friction

D
none of these

Solution

The surface of any body in water behaves as though it is covered with an invisible skin, which allows small, light-weight insects to walk across it. This skin effect is caused by surface tension. Like molecules are attracted to each other. They like to “stick together” and this attractive force is known as cohesion.
Question 3
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Drops are water are created due to-

A
air resistance

B
surface tension

C
gravity

D
all of these

Solution

The shape of the drops is caused by the surface tension of the water. The only reason the drop of water isn't completely spherical is because of the force of gravity pulling down on it. In the absence of gravity, the drop would minimize the surface area in order to minimize tension, which would result in a perfectly spherical shape.
Question 4
1 / -0

Which of the following law is followed by ideal gases?

A
Charle's law

B
Boyle's law

C
Avogadro's law

D
All of the above

Solution

Ans : All of the above
Ideal gas follows Charles Law, Boyles Law and Avogadro's Law. Combining all, we get, PV=nRT which is the ideal gas law.
Question 5
1 / -0

At the boiling point of water, its surface tension

A
Is infinite

B
Is zero

C
Is the same as that at room temperature

D
Is maximum

Solution

As temperature increases, surface molecules escape from the surface. Due to this the interaction force between molecules decreases. As surface tension is the adhesive force of interaction between the molecules, thus surface tension becomes zero.
Question 6
1 / -0

If common salt is dissolved in water, then the Surface Tension of salt water is

A
Increased

B
Decreased

C
Not changed

D
First decreases and then increases

Solution

Adding salt to water will increases the surface tension of water. The strong interactions between the sodium cations and the partial negative oxygen, and the chloride anions and the partial positive hydrogen's, although they disrupt part of the hydrogen bonding that takes place between water molecules, actually strengthen the surface tension of water.
Question 7
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For a non-volatile solute:

A
vapour pressure of solution is more than vapour pressure of solvent

B
vapour pressure of solvent is zero

C
vapour pressure of solute is zero

D
all of the above

Solution

Non-volatile solute always has zero vapour pressure since no vapour is form from solute.
Question 8
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Surface tension may be defined as

A
The work done per unit area in increasing the surface area of a liquid under isothermal condition

B
The work done per unit area in increasing the surface area of a liquid under adiabatic condition

C
The work done per unit area in increasing the surface is of a liquid under both isothermal and adiabatic conditions.

D
Free surface energy per init volume

Solution

Surface tension of a liquid may also be defined as the work done per unit area in increasing the surface area of a liquid under isothermal conditions:
Mathematically, surface tension of the liquid $$T=\dfrac{W}{\Delta A}$$
where $$W$$ is the work done to increase the surface area by $$\Delta A$$.
Question 9
1 / -0

At critical temperature, the surface tension of a liquid is

A
zero

B
infinity

C
the same as that at any other temperature

D
Can not be determined

Solution

Eotvos' Rule states that surface tension is a linear function of temperature following the equation,
$$ \gamma { V }^{ \frac { 2 }{ 3 } }=k({ T }_{ c }-T)$$
where $$\gamma$$ is the surface tension of the liquid.
Almost all liquids approximately follow this equation.
Thus $$T = T_c$$ $$\implies \gamma = 0$$
Hence critical temperature is defined as the temperature at which surface tension of a liquid is zero.
Question 10
1 / -0

Choose the wrong statement from the following?

A
Small droplets of a liquid are spherical due to surface tension

B
Oil rises through the wick due to capillarity

C
In drinking the cold drinks through a straw, we use the phenomenon of capillarity

D
Gum is used to stick two surfaces. In this process we use the property of Adhesion

Solution

For capillary action the diameter of tube should be very small. Liquid rises in the capillary tube due to surface tension. But while drinking cold drinks, we need to create low pressure closer to mouth and due to the pressure difference between the top and the bottom of the straw, cold drink rises. So the rise of cold drink in straw is not due to capillary action.

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States of Matter Test - 21

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States of Matter Test - 21

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SHARING IS CARING

Question 1

Polar water molecules form ion-dipole forces with the ions of $$NaCl$$. Hexane, being nonpolar, cannot form these ion-dipole interactions.

Nonpolar hexane molecules tend to repel the ions that make up $$NaCl$$.

Nonpolar hexane is less dense that water, so when the two are in the same container, any $$NaCl$$ that is added to the mixture sinks to the bottom of the container and cannot get into the hexane layer.

Nonpolar hexane molecules and water molecules repel one another.

Solution

Question 2

viscosity

surface tension

friction

none of these

Solution

Question 3

air resistance

surface tension

gravity

all of these

Solution

Question 4

Charle's law

Boyle's law

Avogadro's law

All of the above

Solution

Question 5

Is infinite

Is zero

Is the same as that at room temperature

Is maximum

Solution

Question 6

Increased

Decreased

Not changed

First decreases and then increases

Solution

Question 7

vapour pressure of solution is more than vapour pressure of solvent

vapour pressure of solvent is zero

vapour pressure of solute is zero

all of the above

Solution

Question 8

The work done per unit area in increasing the surface area of a liquid under isothermal condition

The work done per unit area in increasing the surface area of a liquid under adiabatic condition

The work done per unit area in increasing the surface is of a liquid under both isothermal and adiabatic conditions.

Free surface energy per init volume

Solution

Question 9

zero

infinity

the same as that at any other temperature

Can not be determined

Solution

Question 10

Small droplets of a liquid are spherical due to surface tension

Oil rises through the wick due to capillarity

In drinking the cold drinks through a straw, we use the phenomenon of capillarity

Gum is used to stick two surfaces. In this process we use the property of Adhesion

Solution

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