Question 1

Which Group 15 element is obtained as a by-product of the extraction of other elements?&#10;A) Nitrogen&#10;B) Phosphorus&#10;C) Bismuth.

Accepted Answer

Bismuth is often obtained as a by-product of the extraction of other metals, such as lead, copper, tin, molybdenum, and tungsten, due to its presence in the ores of these metals.

Question 2

Which process is used to prepare nitric acid on an industrial scale?&#10;A) Solvay process&#10;B) Oswald process&#10;C) Haber-Bosch process.

Accepted Answer

The Oswald process, also known as the Ostwald process, is used for the industrial production of nitric acid. This process involves the catalytic oxidation of ammonia to nitric oxide, which is then further oxidized and absorbed in water to produce nitric acid.

Question 3

What are the products of reaction between an s block metal nitride and water?&#10;A) Metal oxide and ammonia&#10;B) Metal hydroxide and ammonia&#10;C) Metal hydroxide and azide

Accepted Answer

When an s block metal nitride reacts with water, the products are metal hydroxide and ammonia. This is because the nitride ion (N^3-) reacts with water to form ammonia (NH3) and hydroxide ions (OH^-), leading to the formation of the metal hydroxide.

Question 4

Which nitrogen hydride is the most basic one? A) NH₃ B) N₂H₄ C) NH₂OH

Accepted Answer

NH₃ (NH3, ammonia) is the most basic nitrogen hydride due to its ability to donate a lone pair of electrons.

Question 5

Relatively low boiling points for PH₃, AsH₃ and SbH₃ can be attributed to: A) low molecular weight B) very weak or non-existent hydrogen bonding C) low vapour pressure at standard conditions.

Accepted Answer

The relatively low boiling points of PH3, AsH3, and SbH3 compared to their group counterparts can be attributed to very weak or non-existent hydrogen bonding. These molecules do not exhibit significant hydrogen bonding because the hydrogen is bonded to elements (P, As, Sb) that are not highly electronegative, unlike the case with water (H2O), where hydrogen bonding is strong due to the high electronegativity of oxygen.

Question 6

Which of the three phosphorus halides, PF₅, PCl₅ and PBr₅ is the strongest Lewis acid? A) PF₅ B) PCl₅ C) PBr₅

Accepted Answer

The strength of a Lewis acid depends on its ability to accept an electron pair. PF5 is the strongest Lewis acid among the given options because fluorine is the most electronegative element, which increases the electron deficiency at the phosphorus atom, making PF5 more eager to accept electron pairs.

Question 7

What are the products of light-induced decomposition of HNO₃? A) NO, O₂ and H₂O B) HNO₂ and H₂O C) NO₂, O₂ and H₂O

Accepted Answer

When HNO3 undergoes light-induced decomposition, it breaks down into NO2, O2, and H2O.

Question 8

Identify the least stable oxide A) P₄O₁₀ B) As₂O₅ C) Bi₂O₅

Accepted Answer

Bi₂O₅ is the least stable oxide because bismuth is a heavier element and its higher oxidation states are less stable compared to lighter elements like phosphorus and arsenic.

Question 9

Determine the charge on triphosphate anion P₃O₁₀^x-: A) 4- B) 5- C) 6-

Accepted Answer

The triphosphate anion has a charge of 5-. This is because in the triphosphate ion, there are three phosphorus atoms each connected by oxygen atoms, and there are four oxygen atoms that are negatively charged (each carrying a -1 charge), leading to a total charge of 5-.

Question 10

Which element of the Group 15 produces the least stable organometallic compounds?&#10;A) As&#10;B) Sb&#10;C) Bi

Accepted Answer

Bi (Bismuth) produces the least stable organometallic compounds among the options given. This is because as we move down the group in the periodic table, the metallic character increases, making the element less effective in forming stable covalent bonds typical of organometallic compounds. Bismuth, being the heaviest among the listed elements, exhibits this trend most strongly.

Deck 15: The Group 15 Elements