Fully eclipsed conformations of butane are most unstable as the groups attached to the two carbon atoms are closest to each other.

Formation of violet colour is due to the presence of Na₃[Fe(CN)₅NOSNa]

An alkaline medium is essentially required for the detection of Ni²⁺ ions with the help of dimethyl glyoxime.

Hence, pH range must be 9 - 11.

Aniline is purified by steam distillation.

Organic compounds in a mixture can be separated best by chromatography. It is the collective term for a set of laboratory techniques for the separation of mixtures. The mixture is dissolved in a fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase. The various constituents of the mixture travel at different speeds, causing them to separate. The separation is based on differential partitioning between the mobile and stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus, change the separation.

In singlet state carbon atom is in sp2 hybridisation state. One of sp2 hybrid orbital contains unshared electron pair with opposite spins and two sp2 hybrid orbitals form two covalent bonds with planar geometry. Net magnetic moment in this state is zero.

The hybrid orbitals used for bonding in methane (sp³), ethane (sp²) and ethyne (sp) have 25, 33 and 50% S-character.

The sp hybridised orbital has 50% 's' character.

The sp² hybridised orbital has 33% 's' character.

The sp³ hybridised orbital has 25% 's' character.

Bond energy increases as the 's' character increases.

Hence, option (1) is correct.

All the carbon atoms in the given compounds are sp² hybridised.

For alkenes other then ethene, addition follows Markowinkov`s rule.

Electron accepting groups which make the substitution difficult are known as deactivating groups. The group or substituent already present on the ring also decides the position of incoming group. Ortho and para directing groups are as follow.

- CH₃, C₂H₅ (- R), - NH₂, - OH, halogens, (Cl, Br, I)

Rates of nitration of benzene and hexadeuterobenzene are the same because the rate determining step,

does not involve the breaking of a carbon-hydrogen bond. Moreover, carbon-deuterium bond is broken more slowly than a carbon-hydrogen bond.

thyne is oxidised by a dilute aqueous solution of potassium permanganate to form oxalic acid. Thus, if ethyne is bubbled through a solution of potassium permanganate, the solution is decolourised. This is Baeyer's test for unsaturated organic compounds.

Ethyne ==> Oxalic Acid (in presence of KMnO₄)

Straight chain olefins have the highest knocking.