P-block Elements MCQ Test

In the contact process for the manufacture of sulphuric acid, V2O5 is used as the catalyst. The contact process involves the oxidation of sulfur dioxide to sulfur trioxide, which is a key step in the production of sulphuric acid. V2O5 acts as a catalyst by providing a surface for the reaction to occur, increasing the rate of the reaction without being consumed itself. It is an effective catalyst for this process due to its ability to promote the desired reaction while remaining stable under the reaction conditions.

The statement "All of these" is correct because H2S is indeed a dibasic acid, meaning it can donate two hydrogen ions. Additionally, H2S acts as a reducing agent, meaning it can donate electrons to other substances. Lastly, H2S does have a distinct rotten egg smell, making all three statements true.

The correct answer is "Both B and C". This is because chlorine can be prepared using both the Deacon process and the electrolysis of brine solution. In the Deacon process, chlorine is produced by reacting hydrogen chloride with oxygen in the presence of a catalyst. On the other hand, electrolysis of brine solution involves passing an electric current through a solution of brine (sodium chloride) to produce chlorine gas at the anode. Therefore, both processes can be used to prepare chlorine.

The structure of XeF6 is distorted octahedral because it has six bonding pairs of electrons and no lone pairs on the central xenon atom. In a regular octahedral structure, all the bond angles would be 90 degrees. However, in XeF6, the presence of six fluorine atoms around the central xenon atom causes repulsion, leading to a distortion in the bond angles. The bond angles in XeF6 are approximately 90 degrees between the axial fluorine atoms and slightly less than 90 degrees between the equatorial fluorine atoms, resulting in a distorted octahedral structure.

The names H2SO3 and H2S2O3 refer to different types of acids. H2SO3 is known as sulphurous acid, while H2S2O3 is called thiosulphuric acid.

Helium is added to oxygen used by deep sea divers because it is less soluble in blood than nitrogen under high pressure. This means that when divers are exposed to high pressure underwater, the helium in the breathing mixture will not dissolve as easily into their bloodstream compared to nitrogen. This is important because if nitrogen were to dissolve in the blood under high pressure, it could lead to a condition called nitrogen narcosis, which can cause confusion and impaired judgment. By using helium instead, the risk of nitrogen narcosis is reduced.

The oxidation state of an element refers to the charge it would have if all its bonds were 100% ionic. In the case of sulphur, it can have oxidation states ranging from -2 to +6. Therefore, the statement that the oxidation state of sulphur is never less than +4 in its compounds is incorrect. Sulphur can form compounds where it has oxidation states of +2, +3, and even -2.

When SO2 gas is passed into an acidified K2Cr2O7 solution, the oxidation number of chromium changes from +6 to +3. This indicates that chromium has undergone reduction, as its oxidation number has decreased. In the reaction, SO2 acts as a reducing agent, causing the chromium in K2Cr2O7 to be reduced from +6 to +3. The sulfur in SO2 is oxidized from an oxidation state of +4 to +6, balancing the reduction of chromium. This change in oxidation numbers is a characteristic of redox reactions, where one species is oxidized and another is reduced.

Liquid NH3, or liquid ammonia, is used as a cooling agent in refrigeration systems. It has a low boiling point and can absorb a large amount of heat when it evaporates, making it an efficient refrigerant. Liquid NH3 is also environmentally friendly, as it does not contribute to ozone depletion or global warming. It is commonly used in industrial refrigeration systems and some commercial applications.

When chlorine is passed over dry slaked lime (calcium hydroxide) at room temperature, the main reaction product is calcium hypochlorite (CaOCl2). This is formed by the reaction between chlorine gas (Cl2) and calcium hydroxide (Ca(OH)2). The reaction can be represented as follows: Ca(OH)2 + 2Cl2 -> CaOCl2 + H2O. Calcium hypochlorite is commonly used as a disinfectant and bleaching agent.

When concentrated H2SO4 is added to charcoal, it reacts with the carbon in the charcoal to produce carbon dioxide (CO2) and sulfur dioxide (SO2). This reaction occurs because H2SO4 is a strong oxidizing agent and charcoal is a good reducing agent. The carbon in the charcoal reduces the sulfur in H2SO4, resulting in the formation of SO2. Additionally, the carbon in the charcoal reacts with the oxygen in H2SO4, producing CO2. Therefore, the correct answer is that SO2 and CO2 are evolved.

HOF is the correct answer because it is the only oxy acid of fluorine that exists. The other options (HFO3, HFO4, HFO2) do not correspond to any known oxy acids of fluorine.

Oleum is the correct answer because it is a solution of sulfuric acid in sulfur trioxide. It is commonly referred to as fuming sulfuric acid or Nordhausen acid. Oleum is highly corrosive and has a strong dehydrating property. It is used in various industrial processes, such as the production of dyes, explosives, and detergents.

The correct answer is sp3d2, square planar. In the molecule XeF4, xenon (Xe) is bonded to four fluorine (F) atoms. The central atom, xenon, has 6 valence electrons. To accommodate the 4 bonding pairs of electrons, xenon undergoes sp3d2 hybridization, resulting in 6 hybrid orbitals. These 6 orbitals are arranged in a square planar geometry around the central xenon atom, with each fluorine atom occupying one of the corners of the square. Therefore, the hybridization and shape of XeF4 is sp3d2, square planar.

Aqua Regia is a highly corrosive mixture used to dissolve gold and platinum. The correct composition of Aqua Regia is 3 parts hydrochloric acid (HCl) to 1 part nitric acid (HNO3). This combination is necessary because HCl provides chloride ions that react with gold, while HNO3 provides nitrate ions that help dissolve the gold chloride complex. The other options listed do not have the correct ratio of acids to effectively dissolve the metals.

H2S is more acidic than H2O because the H-S bond is weaker compared to the H-O bond. In an acidic solution, the compound donates a proton (H+) to the solution. The strength of the bond between the hydrogen atom and the other atom determines how easily the proton can be donated. Since the H-S bond in H2S is weaker than the H-O bond in H2O, it is easier for H2S to donate a proton, making it more acidic.

The dissociation constant (Ka) measures the extent to which a compound dissociates into its constituent ions in solution. In the case of sulphuric acid (H2SO4), it can undergo two dissociation reactions. The first dissociation (Ka1) involves the release of one hydrogen ion (H+) and one sulphate ion (SO4^2-). The second dissociation (Ka2) involves the release of a second hydrogen ion (H+). Since the second dissociation involves the removal of an additional hydrogen ion, it is generally weaker than the first dissociation. Therefore, Ka1 is greater than Ka2 for sulphuric acid.

When chlorine reacts with cold dilute NaOH, it forms sodium hypochlorite (NaOCl), which is compound A. Sodium hypochlorite is commonly known as bleach and is used as a disinfectant and cleaning agent.

When chlorine reacts with hot dilute NaOH, it forms sodium chlorate (NaOCl3), which is compound B. Sodium chlorate is a strong oxidizing agent and is used in the production of herbicides and explosives.

Therefore, the correct answer is NaOCl and NaOCl3.

CCl4 is not a poisonous gas because it is a non-toxic compound. It is commonly known as carbon tetrachloride and is used as a solvent in various industrial applications. Although it was once used as a fire extinguisher and in dry cleaning, its use has been significantly reduced due to its harmful effects on the environment and human health. However, it is not considered a poisonous gas itself.

XeF2 reacts with SbF5 to form a cationic species [XeF]+ and an anionic species [SbF6]-. This reaction occurs because XeF2 acts as a Lewis acid, accepting a pair of electrons from SbF5, which acts as a Lewis base. The resulting complex [XeF]+[SbF6]- is stabilized by the formation of a coordinate bond between the Xe atom and the F atom, and the SbF6- anion provides counter ions to balance the charge.

Sulphuric acid is known for its high acidic character, high affinity for water, and its ability to act as an oxidizing agent. However, it does not exhibit high volatility. Volatility refers to the tendency of a substance to vaporize at a low temperature, and sulphuric acid is not known for easily evaporating or vaporizing. Therefore, high volatility is not a property responsible for the characteristics shown by sulphuric acid.

Fluorine (F2) is the halogen that is most easily reduced. This is because fluorine has the highest electronegativity among all the halogens, meaning it strongly attracts electrons. As a result, it requires less energy to remove an electron from a fluorine atom compared to the other halogens. This makes it easier for fluorine to gain an electron and be reduced in a chemical reaction.

The charring action on carbohydrates shown by sulphuric acid implies that it is a strong dehydrating agent. This means that sulphuric acid has the ability to remove water molecules from the carbohydrates, causing them to break down and form a charred or blackened residue. Dehydration reactions involve the removal of water, and in this case, sulphuric acid facilitates the process by acting as a catalyst.

The correct answer is HOCl

Tincture of iodine is an alcoholic solution of iodine. This solution is commonly used as an antiseptic to disinfect wounds and cuts. The alcohol in the solution helps to prevent the growth of bacteria and the iodine acts as a germicide, killing any microorganisms present. The alcoholic solution allows for easy application and quick drying on the skin.

Both O2 and O3 are not paramagnetic. This is because both O2 and O3 have unpaired electrons, which makes them paramagnetic.

The reactivity of halogens towards H2 is determined by their ability to gain an electron and form a halide ion. The higher the bond enthalpy, the stronger the bond between the halogen atoms, making it more difficult to break and react with H2. From the given bond enthalpies, F-F has the highest bond enthalpy (158 kJ/mol), indicating a stronger bond and less reactivity towards H2. On the other hand, I-I has the lowest bond enthalpy (157 kJ/mol), indicating a weaker bond and higher reactivity towards H2. Therefore, the correct order of reactivity is F2 > Cl2 > Br2 > I2.

When XeF4 undergoes complete hydrolysis, it reacts with water to produce Xe, XeO3, HF, and O2. This is because XeF4 is a covalent compound and can undergo hydrolysis, which is a reaction with water. Xe is formed as a product, along with XeO3, which is xenon trioxide. Additionally, HF (hydrogen fluoride) and O2 (oxygen gas) are also formed during the reaction. Therefore, the correct answer is Xe, XeO3, HF, O2.

The correct answer is Xe+[PtF6]-. This compound is formed by combining xenon (Xe) with the hexafluoridoplatinate(V) ion ([PtF6]-). This reaction is one of the first examples of synthesizing compounds with noble gases, which are typically inert. The positive charge on xenon indicates that it has lost an electron, making it more reactive. The [PtF6]- ion provides the necessary electronegative fluorine atoms to form a stable compound with xenon.

The bond energy is the amount of energy required to break a bond between two atoms. In this case, the correct order of bond energy is F2 > Cl2 > Br2. This means that it takes the most energy to break the bond in F2, followed by Cl2, and then Br2. This is because fluorine (F) has the highest electronegativity and the shortest bond length, resulting in a stronger bond. Chlorine (Cl) has a lower electronegativity and a longer bond length, making its bond weaker than fluorine. Bromine (Br) has an even lower electronegativity and a longer bond length, resulting in the weakest bond of the three.