Question 1

Find the correct statements related to group 15 hydrides. A. Reducing nature increases from NH_3 to BiH_3 B. Tendency to donate lone pair of electrons decreases from NH_3 to BiH_3 C. The stability of

Accepted Answer

Statement A: The reducing nature of group 15 hydrides depends on the E-H bond strength. As the size of the central atom increases down the group, the E-H bond dissociation enthalpy decreases. Hence, the reducing character increases from NH_3 to BiH_3. This statement is correct. Statement B: The basic character or the tendency to donate a lone pair of electrons depends on the electron density on the central atom. As the size of the central atom increases down the group, the electron density decre

Question 2

Treatment of a gas 'X' with a freshly prepared ferrous sulphate solution gives a compound 'Y' as a brown ring. The compounds X and Y are.

Accepted Answer

The brown ring test is used for the detection of nitrate ( NO _3^-) or nitrite ( NO _2^-) ions. In this test, nitric oxide (NO) gas is evolved which reacts with the freshly prepared ferrous sulphate ( FeSO _4) solution to form a brown ring of nitroso ferrous sulphate. The gas X is NO. The reaction is given by: FeSO _4 + NO [ Fe(NO) ] SO _4 The actual composition of the brown ring complex is [ Fe(H _2 O )_5( NO )] SO _4, which is often represented as [ Fe(NO) ] SO _4. Thus, X is NO and Y is [ Fe(

Question 3

Correct statements from the following are: A. Nitrogen in oxidation states from +1 to +4 disproportionates in acid medium. B. Nitrogen has the ability to form d - p multiple bonds with itself and othe

Accepted Answer

Statement A is correct. Nitrogen in oxidation states from +1 to +4 tends to disproportionate in acidic medium. For example, 3HNO_2 HNO_3 + H_2O + 2NO. Statement B is incorrect. Nitrogen does not have d-orbitals in its valence shell, so it cannot form d - p multiple bonds. It forms p - p multiple bonds. Statement C is incorrect. The N-N single bond is weaker than the P-P single bond due to high interelectronic repulsion between the non-bonding electrons, which arises from the small N-N bond lengt

Question 4

Given below are two statements: Statement I: The covalency of oxygen is generally two but it can exceed upto four. The oxidation state of oxygen in SO_2 is -2 and in OF_2 it is +2. Statement II: The a

Accepted Answer

Statement I: The electronic configuration of oxygen is 1s^ 2 2s^ 2 2p^ 4 . Due to the absence of d-orbitals, its maximum covalency is limited to four (using one 2s and three 2p orbitals). Its covalency is generally two, but it can exceed two and go up to four in certain compounds. In SO_2, oxygen is more electronegative than sulphur, so its oxidation state is -2. In OF_2, fluorine is more electronegative than oxygen, so the oxidation state of oxygen is +2. Thus, Statement I is true. Statement II

Question 5

Given below are two statements : Statement (I) : Oxidising power of halogens decreases in the order F_2 > Cl_2 > Br_2 > I_2, which is the basis of "Layer test". Statement (II) : "Layer test" to identi

Accepted Answer

Statement I is true. The oxidising power of halogens decreases down the group in the order F_2 > Cl_2 > Br_2 > I_2. A stronger oxidising halogen can displace a weaker oxidising halogen from its aqueous halide solution. This principle forms the basis of the layer test. Statement II is true. In the layer test, chlorine water (Cl_2) is added to an aqueous solution containing bromide (Br^-) or iodide (I^-) ions. Since Cl_2 is a stronger oxidising agent, it oxidises Br^- to Br_2 and I^- to I_2. The r

Question 6

Given below are two statements : Statement I : The increasing order of boiling point of hydrogen halides is HCl Statement II : The increasing order of melting point of hydrogen halides is HCl In the l

Accepted Answer

Correct order of: (i) Boiling point: HF > HI > HBr > HCl So increasing order: HCl (ii) Melting point: HI > HF > HBr > HCl So increasing order: HCl Both Statement I and Statement II are true.

Question 7

Regarding the hydrides of group 15 elements EH _ 3 ( E = N , P , As , Sb ), select the correct statement from the following: A. The stability of hydrides decreases down the group. B. The basicity of h

Accepted Answer

For group 15 hydrides EH_3 (N, P, As, Sb): Statement A is correct—stability decreases down the group as H-E bond strength decreases. Statement B is correct—basicity decreases as the central atom becomes less electronegative, making it less willing to share electron pairs. Statement C is correct—reducing character increases down the group as the hydrides become easier to oxidize. Statement D is incorrect—boiling points do not consistently increase; NH₃ is anomalously high (-33°C) due to strong hy

Question 8

A ' p '-block element ( E ) and hydrogen form a binary cation ( EH _ x )^ + , while EH _ 3 on treatment with K _ 2 HgI _ 4 in alkaline medium gives a precipitate of basic mercury(II)amido-iodine. Give

Accepted Answer

The p-block element E forms a binary cation (EH_x)^+ with hydrogen and produces a basic mercury(II) amido-iodide precipitate with K_2HgI_4 in alkaline medium. This behavior is characteristic of ammonia (NH₃), which forms the ammonium ion (NH_4)^+ and reacts with Nessler's reagent (K_2HgI_4) to form a characteristic brown/yellow precipitate. Therefore, E is Nitrogen (N), a Group 15 p-block element with electronic configuration 1s^2 2s^2 2p^3. Nitrogen has a notably high first ionization enthalpy

p Block Elements (Group 15, 16, 17 & 18) — Previous Year Questions & Solutions