Chemistry Test - 35

According to the question,

(i)\(\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta_{\mathrm{c}} \mathrm{H}^{\Theta}=-890.3 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

(ii) \(\mathrm{C}\) (s) \(+2 \mathrm{O}_{2}\) (g) \(\rightarrow \mathrm{CO}_{2}(\mathrm{~g}) ; \Delta_{\mathrm{c}} \mathrm{H}^{\Theta}=-393.5 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

(iii) \(2 \mathrm{H}_{2}(\mathrm{~g})+\mathrm{O}_{2}\) (g) \(\rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta_{\mathrm{c}} \mathrm{H}^{\Theta}=-285.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

Thus, the desired equation is the one that represents the formation of \(\mathrm{CH}_{4}(\mathrm{~g})\) that is as follows:

\(\mathrm{C}(\mathrm{s})+2 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{CH}_{4}(\mathrm{~g}) ; \Delta_{\mathrm{f}} \mathrm{H}_{\mathrm{CH}_{4}}=\Delta_{\mathrm{c}} \mathrm{H}_{\mathrm{c}}+2 \Delta_{\mathrm{c}} \mathrm{H}_{\mathrm{H}_{2}}-\Delta_{\mathrm{c}} \mathrm{H}_{\mathrm{CO}_{2}}\)

Substituting the values in the above formula :

Enthalpy of formation \(\mathrm{CH}_{4}(\mathrm{g})=(-393.5)+2 \times(-285.8)-(-890.3)=-74.8 \mathrm{kJmol}^{-1}\)

By the below given relation:

\(\mathrm{pOH}=\mathrm{pK}_{\mathrm{b}}+\log \frac{[\text { Salt }]}{[\text { Base }]}\)

when \([\) Salt \(]=[\) Base \(]\)

And \(\log 1 = 0\)

So, \(\mathrm{pOH}=\mathrm{pK}_{\mathrm{b}}=4.75\)

So, \(\mathrm{pH}=14-4.75=9.25 \)

So, correct match

Condensation:The process by which water vapour in the air is changed into liquid water is called condensation.

This caused the water vapour to condense, or turn into its liquid form.

Condensation is crucial to the water cycle because it is responsible for the formation of clouds.

Sublimation:It is the process in which there is a change of state directly from solid to a gas without changing into a liquid state.

Examples of sublimate substance: Ammonium chloride, Camphor, Iodine, Naphthalene

When ammonium chloride is heated, it gets converted into ammonia and hydrochloric acid.

Common salt (also known as sodium chloride), on the other hand, does not undergo sublimation.

Evaporation:The vaporization occurring from the free surface of a liquid is called evaporation.

Evaporation is the escape of molecules from the surface of a liquid.

This process takes place at all temperatures and increases with the increase of temperature.

Evaporation leads to cooling because the faster molecules escape and, therefore, the average kinetic energy of the molecules of the liquid (and hence the temperature) decreases.

"Acidic hydrogen means it has a tendency to be released as \(H^{+}\) ion. So, if any H-atom is attached to another atom or group of atoms with higher electronegativity, that \(\mathrm{H}\)-atom can be released very easily as \(H^{+}\) ion."

The hydrogen marked with red color is an acidic hydrogen, due to the presence of hydrogens in between electron withdrawing groups.

The hydrogens marked with red color are acidic hydrogens, due to the presence of hydrogens in between electron withdrawing groups.

The hydrogen marked with red color is acidic hydrogen, due to the presence of hydrogens in between electron withdrawing groups.

The hydrogen marked with red color is acidic hydrogen, due to the attachment of hydrogen directly to the oxygen.

Oxygen atoms have higher electronegativity than carbon.

So, the hydrogen which is attached to oxygen is more acidic than the hydrogen atoms that are attached to carbon atoms (carbon atoms later attached to electron withdrawing groups).

Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, and addition of groups to double bonds, are called lyases.A lyase is an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bonds by means other than hydrolysis (a substitution reaction) and oxidation. Lyase-catalyzed reactions break the bond between a carbon atom and another atom such as oxygen, sulfur, or another carbon atom.

Given:

\(a=564 \mathrm{pm} = 564 \times 10^{-10}cm\)

We know that:

The density is given by the formula:

\(\rho=\frac{z M}{a^{3} N_{A}}\)

As we know that,

Each unit cell of \(\mathrm{NaCl}\) has \(4 \mathrm{Na}^{-}\)and \(4 \mathrm{Cl}^{-}\)ions.

\(\Rightarrow z=4\)

Avogadro's number, \(N_{A}=6.022 \times 10^{23} / \mathrm{mol}\)

The total mass of \(\mathrm{NaCl}\):

\(M=22.99+34.34=58.5 \mathrm{~g} / \mathrm{mol}\)

Therefore,

\( \text { Density}\), \(\rho=\frac{z M}{a^{3} N_{A}}\)

\(=\frac{4 \times 58.5}{\left(564 \times 10^{-10}\right)^{3} \times 6.022 \times 10^{23}} \mathrm{~g~cm}^{-3}\)

\(= 2.165 \mathrm{~g~cm}^{-3}\)

The carbon atom is attached with one hydrogen atom and 3 chlorine atom.

It can be seen from structure that chloroform contains 4 single bonds. One single bond contains one sigma.  Therefore, it contains 4 sigma bond.

The physical adsorption of gases on the solid surface is due toVan der wall's force.

When the force of attraction existing between adsorbate and adsorbent are weak Van der wall's of attraction, the process is called Physical Adsorption or Physisorption. When the force of attraction existing between adsorbate and adsorbent are chemical forces of attraction or chemical bond, the process is called Chemical Adsorption.

Given,

[A]₀ = 2 g

[A]_t = 0.2 g

The rate constant for a first order reaction, K= \(4.606 \times 10^{-3} \mathrm{~s}^{-1}\)

For a first order reaction,

\(K=\frac{2.303}{t} \log \frac{[A]_0}{[A]_t}\)

Where,

K = First order rate constant

[A]₀ = Initial concentration

[A]_t = Concentration at time 't'

\(\Rightarrow t=\frac{2.303}{4.606 \times 10^{-3}} \log \frac{2}{0.2}\)

\(\Rightarrow t=\frac{1000}{2} \log {10}\)

As we know,

\(\log {10}=1\)

\(\Rightarrow t=500 ~s\)