Tag: liquid crystals

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Questions Related to liquid crystals

Multiple choice chemistry materials liquid crystals liquid state the liquid state

A liquid cannot be compressed because it has a fixed volume.

  1. True

  2. False

  3. Either

  4. Neither
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

1) A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure.

2) When you compress liquid together, the molecular forces  become very strong stopping it from being compressed very much.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

Hydrogen was collected in one case over water, and in another over mercury in the same conditions. In both cases, the volume of the gas was the same.
Amounts of hydrogen collected over?

  1. Both liquids were identical

  2. The water was greater

  3. The mercury was greater

  4. Noting can be predicted from the given data
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When gas is collected over water, it is saturated with water vapor (Dalton's Law). The total pressure is the sum of gas pressure and water vapor pressure. Over mercury, there is negligible vapor pressure. For the same volume and total pressure, the dry gas amount must be higher in the mercury case.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

Which liquid has maximum surface tension?

  1. Water

  2. Alcohol

  3. Ammonia

  4. Glycerol
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Tension of the surface film of a liquid caused by attraction of the particles in the surface layer by the bulk of the liquid which minimize surface area.
$\bullet $  Water $=72.86$ $nN/m$
$\bullet$  Ethanol (Alcohol) $=22.10$ $nN/m$
$\bullet$  Glycerol $=64.00$ $nN/m$
Ans :- Option A
Multiple choice chemistry materials liquid crystals liquid state the liquid state

When ethanol mixes in cyclohexane reduces the intermolecular forces between ethanol molecule. In this, liquid pair shows:

  1. ${ \Delta H } _{ mix }>0$
  2. ${ \Delta V } _{ mix }<0$
  3. ${ \Delta G } _{ mix }<0$
  4. ${ \Delta H } _{ mix }=0$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
On adding cyclohexane to ethanol . Its molecules get in between the molecules of ethanol thus breaking the hydrogen bonds and reducing ethanol - ethanol interaction .
Thus will increase the vapour pressure of the solution and result in positive deviation from Rouault's law.
Multiple choice chemistry materials liquid crystals liquid state the liquid state

With increase in temperature, the fluidity of liquids 

  1. increases

  2. decreases

  3. remains constant

  4. may increase or decrease
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fluidity is the inverse of viscosity. As temperature increases, the kinetic energy of liquid molecules increases, overcoming intermolecular forces and reducing viscosity, which in turn increases fluidity.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

A liquid of density $1.07\ g/ml$ is filled in the barometer, in place of mercury. What should be the length of liquid column, if another barometer filled with mercury, is measuring $75\ cm$ pressure?

  1. $75\ cm$
  2. $600\ cm$
  3. $9.375\ cm$
  4. $6000\ cm$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice chemistry materials liquid crystals liquid state the liquid state

A beaker is filled with a liquid of density $\rho $ upto a height pressure on the walls is :

  1. 0
  2. $h \rho g $
  3. $h \rho g/2 $
  4. $2 h \rho g $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pressure at a depth h in a liquid is rho * g * h. The average pressure on the walls of a container filled to height h is the integral of pressure over the depth, which results in (1/2) * rho * g * h.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

The latent heat of vaporisation of water is:

  1. $2.25\times 10^6 J/kg$
  2. $2.25\times 10^8 J/kg$
  3. $2.25\times 10^4 J/kg$
  4. $2.25\times 10^{-6} J/kg$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The heat of fusion for water at 0 °C is approximately 334 joules (79.7 calories) per gram, and the heat of vaporization at 100 °C is about 2,250 joules (533 calories) per gram or $2.25 *10^6$ J/kg.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

The boiling point of a liquid with the increase of pressure,  ______________.

  1. decreases

  2. increases

  3. remains constant

  4. changes according to the weather
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since a liquid vaporises when molecules moves faster and farther apart but while increasing pressure, we apply an external force to hold molecules closer to each other. Hence, molecules will require more energy to overcome this resistance thus this increases boiling point of liquid. Hence, the boiling point of a liquid with the increase of pressure, increases.

Multiple choice chemistry materials liquid crystals liquid state the liquid state

Which tool allows liquids to be swirled with a low risk of spilling?

  1. Crucible

  2. Evaporating dish

  3. Tonds

  4. Erlenmeyer flask

  5. Mortar and pestle
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Erlenmeyer flask $\rightarrow$ 

It is used as a container for liquids. Its Shape makes it easy and safe to swirl liquids without spilling, making them ideal for titration. It cannot be used to measure the volume of liquid because its shape makes it difficult to make accurate readings.
Hence the required answer is (C) Erlenmeyer flask.