Conformations of Cyclohexane

Q. In compounds of type $EC{l}_3$, where $E=B,P,As\text{or}Bi$, the $Cl-E-Cl$ bond angles for different $E$ are in the order:

1. $B>P=As=Bi$
2. $B>P>As>Bi$
3. $B<P=As=Bi$
4. $B<P<As<Bi$

Q. Among the structures shown below, which one has the lowest potential energy?

1. 
2. 
3. 
4. 

Q. Which of the following is correct regarding diborane $\left(B_2{H}_6\right)$ ?

1. It has three centred two electron bond
2. Terminal $H-B-H$ bond angle is ${90}^{\circ }$
3. Both Boron atoms are $s{p}^2$ hybridised
4. All hydrogens in $B_2{H}_6$ lie in the same plane

Q. Are the cyclohexane conformations not planar? If yes, why?

1. Because for a planar structure bond angle would be ${120}^o$, too large for $s{p}^3$ hybrid orbitals.
2. Because for a planar structure bond angle would be ${120}^o$, too small for $s{p}^3$ hybrid orbitals.
3. They are planar.
4. Because $s{p}^3$ hybrid orbitals need ${120}^o$ bond angle and cyclohexane planar structure has ${90}^o$

Q. What is the hybridization of phosphine?

1. $s{p}^2$ hybridized
2. $s{p}^3$ hybridized
3. $sp$ hybridized
4. No hybridization

Q. In which of the following compounds, all the bond angles are exactly ${109}^{\circ }{28}^{\prime }$

1. Chloromethane
2. Iodoform
3. Carbon tetrachloride
4. Chloroform

Q. The correct conformation of the following compound is:

1. 
2. 
3. 
4. 

Q. Calorific value of ethane in KJ/g if for the reaction 2C2H6 + 7O2 ---- 4CO2 + 6H20; H= -745.6 kcal 1) -12.4 2) -24.7 3) -52 4) 104

Q. 1, 3 Butadiene on reaction with HBr/water gives primarily 3 bromo 1 butene at high temperatures. Give the reaction.

Q. The degree of unsaturation in the given compound is:
1) $C_3{H}_{3}C{l}_3$
2) $C_3{H}_{4}O$
3) $C_4{H}_{5}N$

1. 2, 1, 3
2. 1, 2, 3
3. 3, 2, 1
4. 2, 3, 1

Q.

From chair, boat, half-chair, and twist, the least stable conformer of cyclohexane is:

1. Half chair

2. Boat

3. Chair

4. Twist

Q. Boat form of cyclohexane is less stable than chair form because:

1. it floats on water
2. of interaction of flag pole H on top of carbon
3. of high dipole moment
4. none of the above

Q. Sort the following cyclohexane conformations according to stability.

1. Half Chair form
2. Chair form
3. Twist Boat form
4. Boat form

Q.

The order of stability of cyclohexane conformations is :

1. Chair $>$ twist boat $>$ boat $>$ half chair

2. twist boat $>$ chair $>$ boat $>$ half chair

3. boat $>$ twist boat $>$ chair $>$ half chair

4. Chair $>$ half chair $>$ boat $>$ twist boat

Q. The species having bond angles of ${120}^{\circ }$ is

1. $P{H}_3$
2. $Cl{F}_3$
3. $NC{l}_3$
4. $BC{l}_3$

Q. Statement-I: The potential energy barrier for rotation about the C=C bond in 2-butene is much higher than that in ethylene.
Statement-II: Hyperconjugation effect decreases the double bond character.

1. Statement-I is True, Statement-II is True ; Statement-II is a correct explanation for Statement-I
2. Statement-I is True, Statement-II is True ; Statement-II is NOT a correct explanation for Statement-I
3. Statement-I is True, Statement-II is False
4. Statement-I is False, Statement-II is True

Q. Glycerine is more viscous than ethylene glycol.

1. True
2. False

Q. Which of the following are known conformations of cyclohexane?

1. Chair
2. Half-chair
3. Boat
4. Twist Boat

Q. Which is more stable and why?

Q. Match compounds (in List I) with the specific properties of the compounds (in List II).

Q. Which of the following statement is correct about alkyl halides?

1. They dissolve in water quickly.
2. They are associated with each other by H-bonds.
3. They dissolve easily in organic solvents.
4. They do not contain any polar bonds in their molecules.

Q. Consider the following transformations:

1. I, II, III
2. II, III
3. I, III
4. I, II

Q. Number of ${90}^{\circ }$ bond angle (s) in $PC{I}_5$ molecule is

Q. Decreasing $-I$ effect of the given group is :
(a) $-CN$ (b) $N{O}_2$ (c)$-N{H}_2$ (d) $-F$

1. $b>a>d>c$
2. $c>b>d>a$
3. $c>b>a>d$
4. $b>c>d>a$

Q. Which of the following statements are false?

1. Glucose is the only aldose that mutarotates
2. Ketose also mutarotates
3. Glycosides mutarotates
4. There is a relationship between the ability of a sugar to mutarotate and to reduce Tollens or Fehling's reagents

Q. Which of the following is the least stable conformer of cyclohexane?

1. 
2. 
3. 
4.