Melting and Boiling point

Q. A solution of urea ( mol.mass 60 g/ mol) boils at 100.18 degrees at the atmospheric pressure . If Kf and Kb for water are 1.86 and 0.512 K Kg/mol respectively, the above solution will freeze at (1) -6.54 degrees (2) 6.54 degrees (3) 0.654 degrees (4) -0.654degrees

Q. why is the enthalpy of vaporization and fusion of deuterium more than that of protium?

Q.

What are the characteristics of coordinate compounds?

Q.

Triple point of water is –

1. 273K

2. 373K

3. 203K

4. 193K

Q. nt10 gms of ice at -10 deg c is mixed with 100 gm of water at 50 deg c contained in a calorimetr weighing 50 gm. (Specific heat of water = 1 cal/gm, Latent heat = 80 cal/gm, specific heat of ice = 0.5 cal/gam/deg c and the specific heat of copper = 0.09 cal/gm/deg c. The final temperature reached by the mixturen

Q. Boiling points of alkyl chloride and alkyl iodide have been compared with alkane.
$\begin{array}{ccc}& & BoilingPoint\\ n-butylchloride& \left(92.5gmo{l}^{-1}\right)& {78.4}^{\circ }C\\ n-hexane& \left(86.2gmo{l}^{-1}\right)& {68.7}^{\circ }C\\ methyliodide& \left(142gmo{l}^{-1}\right)& {42.5}^{\circ }C\\ n-decane& \left(142gmo{l}^{-1}\right)& {164}^{\circ }C\end{array}$

Boiling point of n-hexane is about same as of n-butyl chloride (of same molar mass), while boiling point of n-decane is higher than that of methyl iodide (of same mass). This is due to which of the following?

1. Greater molecular volume of alkanes than alkyl iodide.
2. Compensation of polar effects and molecular volumes in alkyl chloride and alkanes.
3. Both (a) and (b)
4. None of the above

Q. Barring Helium, the melting and boiling points of every noble gas lie within a range of 10 degrees Celsius – True or false?

1. True
2. False

Q.

Rishi is surprised when he sees water boiling at ${115}^{\circ }\mathrm{C}$ in a container. Give reasons as to why water can boil at the above temperature?

Q. 63. If boiling point of an aq. Sol. Is 100.1C what is its freezing point. Given latent heat of fusiin and vapourisation of water are 80 calg-1 and 540 calg-1 resp.

Q.

Which one has the highest boiling point?

1. Ne

2. He

3. Kr

4. Xe

Q. Assertion :Helium and Beryllium have similar outer electronic configuration. Reason: Both are chemically inert.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q.

Choose the correct answer.

Helium is preferred to hydrogen for filling balloons because _____________

1. lighter than air

2. almost as light as hydrogen

3. non-combustible

4. inflammable

Q. Assertion :(A) : Noble gases have very low boiling points. Reason: (R) : All noble gases have general electronic configuration of ${ns}^2{np}^6$ (except $He$)

1. Both (A) and (R) are true but (R) is correct explanation of (A)
2. (A) is false but (R) is true
3. (A) is true but (R) is false
4. Both (A) and (R) are true but (R) is not the correct explanation of (A)

Q. A mixture of He, Ne, Kr and Xe is cooled, Which one of them condenses first ?

1. Ne
2. Xe
3. Kr
4. He

Q. The freezing point of glycerol is 17.8 degree Celsius and its boiling point is 290 degree Celsius. Find its melting and condensation point

Q. Assertion :The boiling points of noble gases increases from $He$ to $Xe$ Reason: The interatomic van der Waals attractive forces increase from $He$ to $Xe$

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q.

Name a triatomic gas.

Q. Barring Helium, the melting and boiling points of every noble gas lie within a range of 10 degrees Celsius – True or false?

1. True
2. False

Q. Why do boiling points of noble gases increase in the order of He to Radon

Q. Kindly explain both the points. These two points are for group-15 elements. [Explain both of these here only as they are similar and short.]
• Boiling points increase down the group
• Melting point increases up to arsenic, and then decreases up to bismuth

Q. Which of the following has the highest boiling point?

1. He
2. Xe
3. $C{H}_4$
4. Ne

Q.

The gas that is not absorbed by coconut charcoal is:

1. Helium

2. Argon

3. Krypton

4. Neon

Q. Which inert gas haves highest boiling point ?

1. Xe
2. He
3. Ar
4. Kr
5. Answer required

Q. There is a steady increase in boiling point from He to Rn.
If true enter 1, else enter 0.

Q. Noble gases are named because of their inertness towards reactivity. Identify an incorrect statement about them.

1. Noble gases have large positive values of electron gain enthalpy
2. Noble gases are sparingly soluble in water
3. Noble gases have very high melting and boiling points
4. Noble gases have weak dispersion forces

Q. Which inert gas having higher boiling point?

1. Xe
2. Ar
3. Kr
4. He

Q. The range of temperature over which noble gases remain liquid is no more than ${10}^{o}C$.

1. True
2. False

Q. Explain why noble gas has the least heat of vaporisation?

Q. Why does boiling points of noble gases increase from helium to radon?

Q. Answer the following with relevant reason.
The boiling points of noble gases' increase with increase in atomic number.