The alkane that can be oxidised to the corresponding alcohol by as per the equation [2024]
(2)
Ordinarily, alkanes resist oxidation but alkanes having tertiary H atom can be oxidised to corresponding alcohols by potassium permanganate.
Given below are two statements:
Statement I : The boiling point of three isomeric pentanes follows the order:
n-pentane > isopentane > neopentane.
Statement II : When branching increases, the molecule attains a shape of sphere. This results in smaller surface area for contact, due to which the intermolecular forces between the spherical molecules are weak, thereby lowering the boiling point.
In the light of the above statements, choose the most appropriate answer from the options given below: [2024]
Both statement I and Statement II are correct.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
A compound with a molecular formula of has two tertiary carbons. Its IUPAC name is [2024]
-hexane
2-methylpentane
2,3-dimethylbutane
2,2-dimethylbutane
(3)
Dihedral angle of least stable conformer of ethane is [2021]
0°
120°
180°
60°
(1)
Dihedral angle of least stable conformer of ethane is 0°. Magnitude of torsional strain depends upon the angle of rotation about C–C bond. This angle is also called dihedral angle or torsional angle. Of all the conformations of ethane, the staggered form has the least torsional strain and the eclipsed form, the maximum torsional strain.
Consider the above reaction and identify the missing reagent/chemical. [2021]
DIBAL-H
Red Phosphorus
CaO
(4)
Which of the following alkane cannot be made in good yield by Wurtz reaction? [2020]
n-Hexane
2,3-Dimethylbutane
n-Heptane
n-Butane
(3)
Wurtz reaction is used for the preparation of higher alkanes containing even number of C-atoms. Thus this reaction cannot be used for the preparation of n-heptane.
The alkane that gives only one monochloro product on chlorination with in presence of diffused sunlight is [2019]
2,2-dimethylbutane
neopentane
n-pentane
isopentane
(2)
In chlorination of alkanes, hydrogen is replaced by chlorine. In neo-pentane, only one type of hydrogen is present, hence replacement of any hydrogen atom will give the same product.
Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is [2018]
(4)
With respect to the conformers of ethane, which of the following statements is true? [2017]
Bond angle changes but bond length remains same.
Both bond angle and bond length change.
Both bond angle and bond length remain same.
Bond angle remains same but bond length changes.
(3)
Conformers of ethane have different dihedral angles but same bond angle and bond lengths.
The correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is [2016]
the eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain.
the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain.
the eclipsed conformation of ethane is more stable than staggered conformation, because eclipsed conformation has no torsional strain.
(2)
Magnitude of torsional strain depends upon the angle of rotation about C—C bond. Staggered form has the least torsional strain and the eclipsed form has the maximum torsional strain. So, the staggered conformation of ethane is more stable than the eclipsed conformation.
