Chemistry Test - 18

Thehexagonal crystal systemconsists of the 7 point groups that have a single six-fold rotation axis. These 7 point groups have 27 space groups (168 to 194), all of which are assigned to thehexagonal lattice system. GraphiteZnO and CdSis an example of acrystalthat crystallizes in thehexagonal crystal system.

The type of isomerism shown by the complex \(\left[\mathrm{CoCl}_2(\mathrm{en})_2\right]\) is geometrical isomerism. This complex shows cis trans isomerism. In the cis form, two \(\mathrm{Cl}\) ligands are adjacent to each other and two en ligands are adjacent to each other. In the trans form, two \(\mathrm{Cl}\) ligands are opposite to each other and two en ligands are opposite to each other.

Carboxylic acids form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen when anhydrous.

Due to the small size and strong hydrogen bonding between the molecule (intermolecular), they overlap and form a dimer in aqueous condition.

For example, acetic acid forms a dimer in the gas phase, where the monomer units are held together by hydrogen bonds.

In the given options all have the same anion \((Cl^-)\), the character of the compounds decided by cation only.

Na, K, Li and Cs belongs to I group and their order of atomic size is:

\(\mathrm{Li}<\mathrm{Na}<\mathrm{K}<\mathrm{Cs}\)

According to Fajan's rule: A bigger cation and smaller anion will favour ionic character.

So, CsCl has a maximum ionic character.

When the ozonolysis of 2-Methyl pent-2-ene take place the products are acetone and propanal.

Antihistamine are not helpful inbringing down acute fever.

Antihistamines are commonly used for:

• Inflammation of the nose and eyes, sneezing.
• Vasodilation-the dilatation of blood vessels, which decreases blood pressure.
• Itching of the eyes, nose and throat.
• To reduce the severity of the rash and itching associated with nettle-type rashes.

The compound \(\mathrm{A}\) is ethanol \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\). The compound \(\mathrm{A}\) on treatment with Na gives sodium ethoxide \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}\right)\) which is compound \(\mathrm{B}\).

\(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \underset{-\mathrm{H}_{2}}{\stackrel{\mathrm{Na}}{\longrightarrow}} \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}\)

The compound \(\mathrm{A}\) on treatment with \(\mathrm{PCl}_{5}\) gives ethyl chloride \(\left(\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{Cl}\right)\) which is compound \(\mathrm{C}\).

\(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} \stackrel{\mathrm{PCl}_{5}}{\longrightarrow} \mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{Cl}+\mathrm{HCl}+\mathrm{POCl}_{3}\)

\(\mathrm{B}\) and \(\mathrm{C}\) react together to give diethyl ether.

\(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}+\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl} \rightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OC}_{2} \mathrm{H}_{5}+\mathrm{NaCl}\)

\(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are in the order \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}\).

Heavy water is denoted by \(D_{2} O\) i.e., deuterium oxide. It is a compound made up of deuterium and oxygen. Deuterium is a heavy isotope of hydrogen, denoted by either \({ }^{2} H\) or \(D\).

• Heavy water is not used as a coolant in nuclear reactors. Rather, it is used as a moderator in nuclear reactors. It is responsible to slow down the speed of fast-moving neutrons and also helps in the control of the nuclear fission process. So, option (A) is incorrect.
• Heavy water \(\left(D_{2} O\right)\) can react with aluminium carbide \(\left(A l_{4} C_{3}\right)\) in a double displacement reaction to produce \(C D_{4}\) and \(A l(O D)_{3}\) as shown below:

\(Al _{4} C _{3}+12 D _{2} O \rightarrow 2 Al ( OD )_{3}+3 C D_{4}\)

So, option (B) is correct.

• Heavy water \(\left(D_{2} O\right)\) can react with calcium carbide \(\left(C a C_{2}\right)\) to produce deutero acetylene \(\left(C_{2} D_{2}\right)\) and calcium deuteroxide ( \(\left.C a(O D)_{2}\right)\) as shown below:

\(CaC _{2}+2 D _{2} O \rightarrow C _{2} D _{2}+ Ca ( OD )_{2}\)

So,option (C) is correct.

• Heavy water \(\left(D_{2} O\right)\) can react with \(S O_{3}\) to form deuterated sulphuric acid \(\left(D_{2} S O_{4}\right)\) as shown below:

\(SO _{3}+ D _{2} O \rightarrow D _{2} SO _{4}\)

As given, the temperature is increased from \(\mathrm{T}_{1}\) to \(\mathrm{T}_{2}\), then new constants become \(\mathrm{k}_{3}\) and \(\mathrm{k}_{4}\) respectively.

Rate constant increases with increase in temperature.

So, \(k_{1}<\mathrm{k}_{3}\) and \(\mathrm{k}_{2}<\mathrm{k}_{4}\)

The given structure is of penicillin.

• Penicillin is a group of antibiotics which includes penicillin G, penicillin V, procaine penicillin and benzathine penicillin.
• Penicillin antibiotics were among the medications to be effective against many bacterial infections caused by staphylococci and streptococci.

The basic chemical structure of all penicillins consists of a beta-lactam ring, a thiazolidine ring, and a side chain (6-aminopenicillanic acid). The antibacterial activity of the penicillins lies within the beta-lactam ring.