Chemistry Test - 20

Iron carbonyl, Fe(CO)₅is mononuclear. In Fe(CO)₅, one Fe atom is surrounded by 5 CO ligands. Mononuclear complexes are those complexes in which one metal atom/ion is surrounded by ligands.

A DNA molecule has two primary structural domains: the DNA backbone and the DNA bases. Recall that all DNA molecules are made from nucleotides. One nucleotide of a DNA molecule consists of a phosphate group, a pentose (five-carbon) sugar called deoxyribose, and a nitrogenous base (adenine, thymine, guanine, cytosine). Several of these nucleotide monomers are joined together by phosphodiester bonds to create a DNA molecule.

The backbone of a DNA molecule consists of the phosphate groups and the deoxyribose sugars, whereas the base region of the DNA molecule consists of the nitrogenous bases; therefore, the backbone of DNA is made up of phosphate groups and pentose sugars. Adenine is part of the base region of the molecule. DNA does not contain any hexose (six-carbon) sugars.

A reaction has both \(\Delta \mathrm{H}\) and \(\Delta \mathrm{S}\) negative. The rate of reaction increases with increase of temperature.

Here,\(\Delta \mathrm{H}=\) Change in enthalpy

and\(\Delta \mathrm{S}=\) change in entropy

There is no relation between spontaneity and rate of reaction as rate of reaction is the measure of how fast is the product formed and spontaneity refers whether the reaction occurs with release of free energy which is set at the specified temperature.In order to increase the rate of the reaction the temperature should be increased as it provides activation energy to the molecule for collision.

If \(\Delta \mathrm{H}\) and \(\Delta \mathrm{S}\) are both negative, \(\Delta \mathrm{G}\) will only be negative below a certain threshold temperature and we say that the reaction is only spontaneous at low temperatures.

The speed at which the reactants are converted to products is called the rate of reaction.The state and number of reactants and complexity of reaction can affect the rate of reaction. According to the law of mass action, the rate of reaction is directly proportional to the concentration of reactants, that is, rate of reaction increases with the increase in concentration of reactants. From this statement we can conclude that the rate of reaction depends upon the concentrations of the reactants which increase the speed of reaction with the increase in chemical reaction.

The IUPAC name of the given compound is 1-chloro-4-methylbenzene.

• When one hydrogen of benzene is replaced by methyl group, then it is called toluene.
• Chlorine will get first priority alphabetically and will be numbered as 1 and methyl will be numbered as 4.
• Chlorine attaches at para position is also called p-chlorotoluene or 4-chlorotoluene.

The hydrogens between two keto groups are highly acidic.

Gas-gas colloidal system is not possible as we can't distinguish between the dispersed phase and dispersed medium.

A colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium.

The essential difference between a solution and a colloid is that of particle size. While in a solution, the constituent particles are ions or small molecules. In a colloid, the dispersed phase may consist of particles of a single macromolecule (such as protein or a synthetic polymer) or an aggregate of many atoms, ions or molecules.

Stability depends on the electronic configurations of respective ions/elements.

\(F e^{+3}\) has an electronic configuration of \([A r] 3 d^{5} 4 s^{0}\).

\(F e^{+2}\) has an electronic configuration of \([A r] 3 d^{6} 4 s^{0}\).

\(F e^{+3}\)being half filled is more stable than \(\mathrm{Fe}^{+2}\) which is incompletely filled.

Ammonia gas is produced when calcium nitride \(\left(\mathrm{Ca}_{3} \mathrm{N}_{2}\right)\) is hydrolyzed by water.

The reaction is given as follows:

\(\mathrm{Ca}_{3} \mathrm{N}_{2}+6 \mathrm{H}_{2} \mathrm{O} \rightarrow 3 \mathrm{Ca}(\mathrm{OH})_{2}+2 \mathrm{NH}_{3}\)

Thus, the gas formed is ammonia.

The compound \( (B)\) is represented by option \( (B)\). Sodium methoxide is a strong base and abstracts acidic \(H\) atom of acetylene to form acetylide ion. The acetylide ion then attacks alkyl bromide and displaces bromide ion to form \(C - C\) single bond. Ester group is hydrolyzed to give primary alcoholic-\(OH\) group.