General trends, Group 15 and 16
- Given below are two statements :Statement I : Like nitrogen that can form ammonia, arsenic can form arsine.Statement II : Antimony cannot form antimony pentoxide.In the light of the above statements, choose the most appropriate answer from the option… Answer: 3. Statement I is correct but Statement II is incorrect Key idea: group 15 elements form hydrides EH₃ and oxides E₂O₅ . Statement I... 1
- The products A and B obtained in the following reactions, respectively, are3ROH + PCl_3 → 3RCl + AROH + PCl_5 → RCl + HCl + B Answer: 1. H₃PO₃ and POCl₃ Key idea: phosphorus halides convert ROH into RCl, and the phosphorus part ends as an acid or oxychloride. 3ROH+P... 1
- Given below are two statements:Statement I : The boiling point of hydrides of Group 16 elements follow the orderH_2O > H_2Te > H_2Se > H_2S.Statement II : On the basis of molecular mass, H_2O is expected to have lower boiling point than the other mem… Answer: 2. Both Statement I and Statement II are true. Key idea: boiling point of hydrides depends on H-bonding and on molecular mass. H₂O i... 1
- Among Group 16 elements, which one does NOT show -2 oxidation state? Answer: 1. Po Key idea: metallic character increases down the group, so the -2 state becomes unfavourable. O, S, Se and Te form oxides, sulp... 1
- Match List - I with List - II :List - I (Oxoacids of Sulphur): A. Peroxodisulphuric acid B. Sulphuric acid C. Pyrosulphuric acid D. Sulphurous acidList - II (Bonds): I. Two S-OH, Four S=O, One S-O-S II. Two S-OH, One S=O III. Two S-OH, Four S=O, One… Answer: 3. A-III, B-IV, C-I, D-II Key idea: Draw the structure of each oxoacid. A. H₂S₂O₈ , peroxodisulphuric: two S-OH, four S=O and one S-... 1
- The pollution due to oxides of sulphur gets enhanced due to the presence of :(a) particulate matter(b) ozone(c) hydrocarbons(d) hydrogen peroxideChoose the most appropriate answer from the options given below : Answer: 3. (a), (b), (d) only Key idea: SO₂ is converted to SO₃ and then to sulphuric acid faster when oxidants or surfaces are present. Par... 1
- Given below are two statements :Statement I :The boiling points of the following hydrides of group 16 elements increases in the order -H_2O < H_2S < H_2Se < H_2Te.Statement II :The boiling points of these hydrides increase with increase in molar mass… Answer: 3. Both Statement I and Statement II are incorrect. Key idea: water has an abnormally high boiling point because of hydrogen bonding... 1
- Which of the following oxoacid of sulphur has -O-O- linkage ? Answer: 3. H ₂ S ₂ O ₈ , peroxodisulphuric acid The peroxo linkage -O-O- is present in peroxoacids. H₂S₂O₈ (peroxodisulphuric acid, Marshall... 1
- Identify the incorrect statement related to PCl_5 from the following : Answer: 4. PCl ₅ molecule is non-reactive PCl₅ is trigonal bipyramidal. Three equatorial P-Cl bonds are at 120 to each other: correct. Two a... 1
- Which is the correct thermal stability order for H_2E (E = O, S, Se, Te and Po) ? Answer: 3. H ₂ Po < H ₂ Te < H ₂ Se < H ₂ S < H ₂ O Thermal stability of hydrides of group 16 depends on the E-H bond strength, which falls... 1
- Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity ? Answer: 1. N ₂ O ₅ N₂O , NO and NO₂ are all released by natural processes (soil bacteria, lightning) and by human activity (fuel combustion,... 1
- In which pair of ions both the species contain S-S bond ? Answer: 1. S₄O₆²⁻, S₂O₃²⁻ Key idea: draw the structures. mathrmS₄O₆²⁻ (tetrathionate): has an S-S bond in the chain O₃S-S-S-SO₃ . mathrmS₂O₃... 1
- Name the gas that can readily decolourise acidified KMnO_4 solution : Answer: 1. SO₂ Key idea: KMnO₄ is decolourised by a reducing gas. SO₂ is a reducing agent: 5SO₂ + 2MnO₄^- + 2H₂O → 5SO₄²⁻ + 2Mn²⁺ + 4H^+ . P... 1
- Which of the following fluoro-compounds is most likely to behave as a Lewis base? Answer: 1. PF₃ Key idea: a Lewis base needs a lone pair to donate. PF₃ : P has a lone pair, so it can act as a donor. CF₄ : no lone pair and... 1
- Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour? Answer: 3. CaF₂ + H₂SO₄ → CaSO₄ + 2HF Key idea: oxidising behaviour means H₂SO₄ is reduced (S goes from +6 to +4 as SO₂ ). Options 1, 2, 4:... 1
- When copper is heated with conc. HNO_3 it produces : Answer: 1. Cu(NO₃)₂ and NO₂ Key idea: the reduction product of nitric acid depends on its concentration. Cu+4HNO₃(conc.)→ Cu(NO₃)₂+2NO₂+2H₂O... 1
- The product obtained as a result of a reaction of nitrogen with CaC_2 is : Answer: 1. Ca(CN)₂ Key idea: calcium carbide absorbs nitrogen at high temperature to give calcium cyanamide (nitrolim) and carbon. CaC₂+N₂→... 1
- Which is the correct statement for the given acids ? Answer: 2. Phosphinic acid is a monoprotic acid while phosphonic acid is a diprotic acid. Key idea: only the P-OH hydrogens are acidic. Phos... 1