Melting and Boiling Points

Q.

p - dichlorobenzene has higher melting point and lower solubility than those of o - and m-isomers. Discuss. ?

Q.

The isomer of dichlorobenzene which has highest boiling point

1. m-dichlorobenzene

2. 1, 2 dichlorobenzene

3. p-dichlorobenzene

4. o-dichlorobenzene

Q. In first transition series, the melting point of Mn is low because

1. Due to configuration, metallic bonds are strong
2. None of these
3. Due to configuration, metallic bonds are weak
4. Due to configuration, metallic bonds are weak

Q.

Why does the temperature of a substance remain constant during its melting point or boiling point?

Q.

Which is the correct increasing order of boiling points of the following compounds?

1-iodobutane , 1-bromobutane, 1-chlorobutane, Butane

(a) Butane < 1-chlorobutane < 1-bromobutane < 1-iodobutane

(b) 1-iodobutane < 1-bromobutane < 1-chlorobutane < Butane

(c) Butane < 1-iodobutane < 1-bromobutane < 1-chlorobutane

(d) Butane < 1-chlorobutane < 1-iodobutane < 1-bromobutane

Q. Which of the following isomer has the highest melting point?

1. o-Dichlorobenzene
2. p-Dichlorobenzene
3. m-Dichlorobenzene
4. All have the same melting point

Q.

The boiling points of diethyl ether, acetone and n-butyl alcohol are $35°\mathrm{C},56°\mathrm{C}\mathrm{and}118°\mathrm{C}$ respectively. Which one of the following correctly represents their boiling points in the kelvin scale?

1. $306\mathrm{K},329\mathrm{K},391\mathrm{K}$

2. $308\mathrm{K},329\mathrm{K},392\mathrm{K}$

3. $308\mathrm{K},329\mathrm{K},391\mathrm{K}$

4. $329\mathrm{K},392\mathrm{K},308\mathrm{K}$

Q. A solid melt slightly above 273 K and is a poor conductor of heat and electricity. To which of the following categories does it belong?

1. Ionic solid
2. Covalent solid
3. Metallic solid
4. Molecular solid

Q. Which of the following elements have the highest melting points?

1. All the d block transition metals have melting points that are close to each other
2. Metals belonging the 3d transition series
3. Metals of the 5d transition series
4. Metals of the 4d transition series

Q.

Which is the correct increasing order of boiling points of the following compounds?

1-bromoethane, 1-bromopropane , 1-bromobutane, Bromobenzene

(a) Bromobenzene < 1-bromobutane < 1-bromopropane < 1-bromoethane

(b) Bromobenzene < 1-bromoethane < 1-bromopropane < 1-bromobutane

(c) 1- bromopropane <1-bromobutane < 1- bromoethane < Bromobenzene

(d) 1-bromoethane < 1-bromopropane < 1-bromobutane < Bromobenze

Q. Arrange the following in increasing order of their boiling points.

1. ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{Br}$
2. ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{Br}$
3. $({\mathrm{CH}}_3{)}_2{\mathrm{CHCH}}_2\mathrm{Br}$
4. $({\mathrm{CH}}_3{)}_3\mathrm{CBr}$

Q.

Which of the following systems has maximum number of unpaired electrons in an inner octahedral complex?

1. d⁴

2. d⁷

3. d⁹

4. d⁵

Q. 39. Para dichlorobenzene has higher melting point and solubility than those of ortho and meta isomer.why?

Q.

Why are Alkali Metals are soft?

Q.

When ice melts into water, heat is

1. evolved

2. absorbed

3. no change

4. evolved or absorbed depending upon the conditions

Q.

Assertion : Alkyl halides are soluble in organic solvents.
Reason : p-dichlorobenzene possesses low melting point.

1. If both assertion and reason are true and the reason is the correct explanation of the assertion.

2. If both assertion and reason are true but reason is not the correct explanation of the assertion.

3. If assertion is true but reason is false.
4. If the assertion and reason both are false.

5. If assertion is false but reason is true.

Q.

Which has highest melting point

1. LiCl

2. BeCl₂

3. BCl₃

4. CCl₄

Q. Which one of the following form maximum boiling point azeotrope ? (1) CHCl3 + C2H5OH (2) Ethanol + water (3) Benzene + toluene (4) HCl + water Why option 1 is incorrect?

Q.

Why some metals are soft?

Q. On what basis hydrides are classified into ionic, covalent and metallic hydrides?

Q. Choose the correct statement(s) related to conformers of n-Butane (about $C_2-C_3$ bond).

1. Dipole moment of gauche conformer is non-zero
2. Dipole moment of anti conformer is non-zero
3. Dipole moment of gauche conformer is zero
4. Dipole moment of anti conformer is zero

Q. AgCl on fusion with sodium carbonate gives: (1) Ag2CO3 (2) Ag2O (3) Ag (4) Ag2C2

Q. p-Dichlorobenzene has higher melting point than those of o- and m-isomers. Discuss.

Q. Which of the following property is not a similarity between Boron and silicon?

1. Non-metals metals
2. used as semiconductors
3. formation of covalent hydrides
4. None of the above

Q. The number of chiral centres in penicillin is/are:

Q. Arrange the following compounds in increasing order of their boiling points.
I. $C{H}_{3}C{H}_{2}C{H}_{2}Br$
II. $C{H}_{3}C{H}_{2}C{H}_{2}C{H}_{2}Br$
III.$(C{H}_3{)}_{2}CHC{H}_{2}Br$
IV. $(C{H}_3{)}_{3}CBr$

1. IV < III < II < I
2. I < IV < III < II
3. III < I < IV < II
4. II < I < III < IV

Q. In a compound of hydrocarbon , carbon contains 81.81%and 18.18%hydrogen .calculate molecular formula of compound?

Q. Gold crystallises in ccp structure .the total number of voids present in 197g of gold will be .

Q. Same halogen atom (-X), increased in the size of the alkyl chain $C{H}_{3}Cl,C{H}_{3}C{H}_{2}Cl,C{H}_3(C{H}_2{)}_{2}Cl,C{H}_3(C{H}_2{)}_{3}Cl$
What is the effect on the boiling point and the density?

1. Boiling point increases, density increases
2. Boiling point increases, density decreases
3. Boiling point decreases, density decreases
4. Boiling point decreases, density increases

Q. ) Which of the following is the least volatile?(1) CH3-CH2 -CH2-F(2) CH3-CH2-CH2_-Cl(3) CH, -CH-CH, (4) CH3 -CH2-CH2 Br