Chemistry Test-28

Ethynehas same hybridization as its combustion product, \(\mathrm{CO}_{2}\).

The structure of \(\mathrm{CO}_{2}\) is as follows:

\(\mathrm{O}=\mathrm{C}=\mathrm{O}\)

Here, carbon is sp hybridised.

The structure of ethyne is as follows:

\(\mathrm{CH} \equiv \mathrm{CH}\)

Here also, both carbon atoms are sp hybridised.

Binding Energy of the nucleus: The energy that holds a nucleus together or the energy required to disassemble a nucleus into its constituent protons and neutrons completely is called binding energy. The energy that would be liberated by combining individual protons and neutrons into a single nucleus is called binding energy.

• The total binding energy of an element is the product of binding energy per nucleon and mass number.
• If in a reaction total binding energy of the resultant products is more than the total binding energy of the reactant products then in the reaction energy is absorbed and similarly vice-versa.

Total binding energy of \(A=E_{A}=5 \times 30=150 \mathrm{MeV}\)

Total binding energy of \(B=E_{B}=8.5 \times 60=510 \mathrm{MeV}\)

Total binding energy of \(\mathrm{C}=\mathrm{E}_{\mathrm{C}}=8 \times 90=720 \mathrm{MeV}\)

Total binding energy of \(D=E_{D}=7 \times 120=840 \mathrm{MeV}\)

Calculation of final and initial energies of elements for each of the reactions.

Reaction (a) \(D\rightarrow 2B\)

\(2 E_{B}-E_{D}=2(510)-840=180 \mathrm{MeV}\)

\(180>0\)

So energy is absorbed in this reaction.

Reaction (b)\(C\rightarrow B + A\)

\(E_{B}+E_{A}-E_{C}=510+150-720=-60 \mathrm{MeV}\)

\(-60<0\)

So energy is released in this reaction.

Reaction (c) \(B\rightarrow 2 \mathrm{~A}\)

\(2 E_{A}-E_{B}=2(150)-510=-210 \mathrm{MeV}\)

\(-210<0\)

So energy is released in this reaction.

So energy is released in (b) and (c) reaction.

Peroxyacetyl nitrate (PAN) is used in the photochemical song.

Indigo is a vat dye. Dyeing with indignation was carried out in the wooden vats in the form of water-soluble indigotin-white.

IR active molecules are used in global warming.

Dioxins are used to burn the waste into ashes.

Number of isomeric primary amines obtained from \({C}_{4} {H}_{11} {~N}\) are \(4\).

The possible isomers are:

\({CH}_{3} {CH}_{2} {CH}_{2} {CH}_{2} {NH}_{2}\)

\(\left({CH}_{3}\right)_{2}-{CH}-{CH}_{2} {NH}_{2}\)

\(\left({CH}_{3}\right)_{3}-{NH}_{2}\)

\({CH}_{3}-{CH}\left({NH}_{2}\right) {CH}_{2}-{CH}_{3}\)

Molar mass of a compound describes the total mass of \(6.023 \times 10^{23}\) atoms or particles of the compound.

Example: Molar mass of \(\mathrm{H}_{2}=2 \mathrm{~g}\)

Some of the metals react with dilute acid, forming metal salt and hydrogen, while a few do not react with dilute acids.

Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because \(\mathrm{HNO}_3\) is a strong oxidizing agent. It oxidises the \(\mathrm{H}_2\) produced to water and itself gets reduced to any of the nitrogen oxides \(\left(\mathrm{N}_2 \mathrm{O}, \mathrm{NO}, \mathrm{NO}_2\right)\).

Natural rubberis a linear polymer of isoprene.

Natural rubber is obtained from latex, a milky liquid present in either the latex vessels (ducts) or in the cells of rubber-producing plants. Around 20,000 species of plants produce latex, but only 2,500 species have been found to contain rubber in their latex.

Decomposition reaction is a reaction where a single compound breaks and gives us two or more products.

In the first option \(\mathrm{Ag^{+}(a q)+C l^{-}(a q) \rightarrow A g C l(s)}\), here two different ions are combining to give a single product thus this is not a decomposition reaction.

In the third option \(\mathrm{NH_{3}(l)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{NH}_{4}^{+}(a q)+\mathrm{OH}^{-}(a q)}\), here the ammonia has dissolved in water and formed ions in the solution thus this is not a decomposition reaction either.

In the fourth option \(\mathrm{HC_{2} \mathrm{H}_{3} \mathrm{O}_{2}(l)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}{ }^{-}(a q)}\) where a proton transfer is taking place thus this is not a decomposition reaction.

But in the second option \(\mathrm{CaCO_{3}(s) \rightarrow \mathrm{CaO}(s)+\mathrm{CO}_{2}(g)}\) the calcium carbonate decomposes into calcium oxide and carbon dioxide gas is liberated. So, \(\mathrm{CaCO_{3}(s) \rightarrow \mathrm{CaO}(s)+\mathrm{CaO}_{2}(g)}\) is a decomposition reaction.

The state in which \(\mathrm{NaCl}\) is a bad conductor of electricity is solid and the state in which \(\mathrm{NaCl}\) is a good conductor of electricity is molten.

\(\mathrm{NaCl}\) is a bad conductor of electricity in the solid-state as there are no free ions. In the molten state, the ions are free to move around and therefore, can conduct electricity.

Ideal solution:

The solutions which obey Raoult's law are known as Ideal solution.

The two important properties of ideal solution is:

• The enthalpy of mixing is zero.
• The volume of mixing is always zero.

Option (A), (B) is not possible as \(\Delta \mathrm{H}_{\text {mixing }}\) should be zero. \(\Delta \mathrm{H}_{\text {mixing }}\) cannot be greater than zero or less than zero.

So, both \(\mathrm{A}\) and \(\mathrm{B}\) are wrong.

At molecular level, ideal behaviour of the solutions can be explained by considering two components \(\mathrm{A}\) and \(\mathrm{B}\).

In pure components, the intermolecular attractive interactions will be of types \(\mathrm{A}-\mathrm{A}\) and \(\mathrm{B}-\mathrm{B}\), whereas in the binary solutions in addition to these two interactions, A-B type of interactions will also be present. If the intermolecular attractive forces between the \(\mathrm{A}-\mathrm{A}\) and \(\mathrm{B}-\mathrm{B}\) are nearly equal to those between \(\mathrm{A}-\mathrm{B}\), this leads to the formation of ideal solution.