OC-2021 Flashcards
Dipoledipole interactions are present in _____.
A. HCl B. C6H6 C. CH4 D. NaCl
HCl
Non-polar atoms and molecules condense due to _____.
A. iondipole interaction
B. polarizability dispersion forces
C. van der Waals forces
D. dipoledipole attraction
B. van der Waals forces
A compound having a permanent dipole moment is _____.
A. CO2
B. H2
C. CH4
D. CO
CO
“dipole moment” = polar
Which element can take part in hydrogen bonding?
A. F
B. O
C. N
D. all of them
D. all of them
all are highly electronegative elements
Polarizability is highest for _____.
A. CH4 B. H2 C. CCl4 D. H2S
C. CCl4
A compound which hydrogen bonds is _____.
A. BeH2
B. CH4
C. CH3COOH
D. C2H6
C. CH3COOH
The force due to hydrogen bonding must be overcome in the boiling of _____.
A. CH3OCH3
B. NH3
C. SbH3
D.C2H5OC2H5
B. NH3
Note: determine which one will undergo hydrogen bonding
other options are dipole dipole and vdw
The hydrocarbon having the lowest boiling point is _____.
A. C4H10
B. CH4
C. C6H6
D. C2H6
B. CH4
low molecular size = low BP
Which of the following has the lowest boiling point?
A. CH3COCH3
B. CH3OCH3
C. CH3COOH
D.CH3CHO
B. CH3OCH3
an ether.
Other options are DD, HB, and DD which is higher in BP
Note. DRAW
Arrange the following according to increasing boiling point:
W= methyl acetate
X= butanal
Y= n-butyl alcohol
Z = butanoic acid
methy acetate < butanal < n-butyl alcohol < butanoic acid
Which of the following has the lowest boiling point?
A. o-hydroxynitrobenzene
C. p-hydroxynitrobenzene
B. m-hydroxynitrobenzene
D. p-hydroxybenzoyl chloride
o-hydroxynitrobenzene
BP: mono < ortho < meta < para
Which of the following statements is correct?
A. The greater the molecular weight, the lower the b.p
B. The greater the molecular attraction, the higher the b.p
C. The greater the molecular attraction, the lower the HV
D. The smaller the molecular weight, the higher the b.p
The greater the molecular attraction, the higher the b.p
Melting Point
I (aldehyde) – Lowest melting point.
IV (meta-nitrobenzoic acid) – Slightly higher due to hydrogen bonding.
II (para-nitrobenzoic acid) – Stronger hydrogen bonding, para position increases symmetry and packing efficiency.
III (sodium salt) – Highest due to ionic bonding.
The vapor pressure of a liquid depends on the _____.
A. amount of liquid
C. temperature of the liquid
B. volume of the liquid
D. surface area of the liquid
C. temperature of the liquid
A liquid having a higher vapor pressure will have _____.
A. higher molecular weight
C. higher boiling point
B. lower boiling point
D. higher surface area
B. lower boiling point
Which of the following properties indicates very strong intermolecular forces in liquids?
A. very low surface tension
C. very low boiling point
B. very low critical temperature
D. very low vapor pressure
D. very low vapor pressure
Rank the following compounds in the order of increasing basicity:
I.p-nitroaniline
II. p-aminobenzaldehyde
III. N-methylaniline
IV. p-methylaniline
I.p–nitroaniline
II. P-aminobenzaldehyde
IV p-methyaniline
III. N-methylaniline
Arrange according to increasing acidity
I. methanol
II. ethanol
III. Phenol
IV. p-nitrophenol
V. p-bromophenol
ethanol < methanol < phenol < p-bromophenol
Arrange the following according to increasing acid strengths:
W= benzoic acid
Y= 4-cyanobenzoic acid
X= 4-methoxybenzoic acid
Z = 4-methylbenzoic acid
XZWY
methoxy < methyl < benzoic < cyano
: X (–OCH3) < Z (–CH3) < W (no group) < Y (–CN).
- Which of the following molecules has a linear geometry?
a. water (H2O)
c. carbon dioxide (CO2)
b. ammonia (NH3)
d. boron trifluoride (BF3)
c. carbon dioxide (CO2)
The most stable among the following free radicals is
a. CH3 ?
b. (CH3)3C ?
c. (CH3)2CH ?
d. (CH3)2CHCH2
c. (CH3)2CH ?
high no. of C atoms = low stability
high no. of branching = high stability
The stability of free radicals follows the order: tertiary > secondary > primary > methyl
- Which of the following is TRUE about cis and trans alkenes?
a. Cis alkenes are less polar.
b. Cis alkenes have higher boiling points.
c. Trans alkenes are more polar.
d. Trans alkenes have higher boiling points.
b. Cis alkenes have higher boiling points.
Cis alkenes are more polar than trans alkenes due to the arrangement of substituents on the same side of the double bond, which creates a net dipole moment. This leads to stronger intermolecular forces (dipole-dipole interactions) in cis alkenes, resulting in higher boiling points compared to their trans counterparts. Trans alkenes, on the other hand, tend to cancel out dipoles due to the symmetry, making them less polar and giving them lower boiling points.
- How many distinct acyclic compounds have the formula C5H10?
a. 3
b. 4
c. 5
d. 6
5
- Which compound will rapidly decolorize bromine in CHCl3?
a. hexane
c. 1-hexene
b. benzene
d. cyclohexane
c. 1-hexene