Electronic configuration and general trends, Group 13 and 14
- Given below are two statements :Statement I : The nutrient deficient water bodies lead to eutrophication.Statement II : Eutrophication leads to decrease in the level of oxygen in the water bodies.In the light of the above statements, choose the corre… Answer: 1. Statement I is incorrect but Statement II is true. Key idea: Eutrophication is caused by nutrient enrichment. Statement I is fals... 1
- Taking stability as the factor, which one of the following represents correct relationship? Answer: 1. TlI > TlI ₃ Key idea: In group 13 the +1 state becomes more stable down the group because of the inert pair effect; for Tl, +1 is... 1
- Match List - I with List - II :List - I: A. Coke B. Diamond C. Fullerene D. GraphiteList - II: I. Carbon atoms are sp^3 hybridised. II. Used as a dry lubricant III. Used as a reducing agent IV. Cage like moleculesChoose the correct answer from the op… Answer: 4. A-III, B-I, C-IV, D-II Key idea: Match each form of carbon with its structure or use. A. Coke is used as a reducing agent in meta... 1
- Match List - I with List - II.List - I (Hydrides): (a) MgH_2 (b) GeH_4 (c) B_2H_6 (d) HFList - II (Nature): (i) Electron precise (ii) Electron deficient (iii) Electron rich (iv) IonicChoose the correct answer from the options given below : Answer: 2. (a) - (iv), (b) - (i), (c) - (ii), (d) - (iii) Key idea: classify hydrides by electron count. MgH₂ : metal hydride of s-block, io... 1
- Which of the following statement is not correct about diborane ? Answer: 1. Both the Boron atoms are sp² hybridised. Key idea: in diborane each boron is sp³ hybridised, not sp² . Each B uses four sp³ orbit... 1
- Choose the correct statement : Answer: 4. Diamond is sp³ hybridised and graphite is sp² hybridized. Key idea: diamond and graphite are both covalent forms of carbon with d... 1
- Among the following alkaline earth metal halides, one which is covalent and soluble in organic solvents is : Answer: 4. Beryllium chloride Key idea: small, highly polarising mathrmBe²⁺ gives strong covalent character (Fajans' rules). BeCl₂ is covale... 1
- Which of the following is not correct about carbon monoxide ? Answer: 3. The carboxyhaemoglobin (haemoglobin bound to CO) is less stable than oxyhaemoglobin. CO binds to haemoglobin to form carboxyhaemo... 1
- Match the following and identify the correct option.(a) CO(g) + H_2(g) (i) Mg(HCO_3)_2 + Ca(HCO_3)_2(b) Temporary hardness of water (ii) An electron deficient hydride(c) B_2H_6 (iii) Synthesis gas(d) H_2O_2 (iv) Non-planar structure Answer: 1. (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv) (a) CO+H₂ is water gas, called synthesis gas: (iii). (b) Temporary hardness is due to Mg(H... 1
- Identify the correct statements from the following :(a) CO_2(g) is used as refrigerant for ice-cream and frozen food.(b) The structure of C_60 contains twelve six carbon rings and twenty five carbon rings.(c) ZSM-5, a type of zeolite, is used to conv… Answer: 4. (c) and (d) only Check each statement. (a) Solid CO₂ (dry ice) is the refrigerant for ice-cream and frozen food, not the gas. The... 1
- Which of the following species is not stable ? Answer: 4. [SiCl₆]²⁻ Key idea: silicon (period 3) can expand its octahedral coordination, but only with small ligands. mathrm[SiF₆]²⁻ is kno... 1
- Among the following, the one that is not a green house gas is : Answer: 4. sulphur dioxide Greenhouse gases absorb infrared radiation re-emitted by the Earth. N₂O , CH₄ and O₃ (and CO₂ , CFCs) all do. SO₂... 1
- Which of the following is incorrect statement ? Answer: 1. PbF ₄ is covalent in nature Go through the statements. PbF₄ is ionic (Pb(IV) with the very electronegative F), so the statement '... 1
- Match the following :(a) Pure nitrogen (i) Chlorine(b) Haber process (ii) Sulphuric acid(c) Contact process (iii) Ammonia(d) Deacon's process (iv) Sodium azide or Barium azideWhich of the following is the correct option ? Answer: 4. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i) (a) Pure nitrogen: obtained by heating sodium azide or barium azide, (iv). (b) Haber proce... 1
- Which one of the following elements is unable to form MF_6^3- ion ? Answer: 2. B mathrmMF₆³⁻ needs six F^- around M, so M must use d orbitals to exceed an octet. Boron is in period 2 and has no d orbitals; it... 1
- Which of the following is a sink for CO ? Answer: 1. Micro organisms present in the soil Key idea: CO is removed from air mainly by soil micro-organisms. Certain soil bacteria and fu... 1
- It is because of inability of ns^2 electrons of the valence shell to participate in bonding that : Answer: 4. Sn²⁺ is reducing while Pb⁴⁺ is oxidising Key idea: the inert pair effect makes the +2 state more stable than +4 in heavy group 14... 1
- Boric acid is an acid because its molecule Answer: 2. accepts OH^- from water releasing proton Key idea: boric acid is a Lewis acid, not a proton donor. Boron in B(OH)₃ has an empty p... 1
- AlF_3 is soluble in HF only in presence of KF. It is due to the formation of Answer: 1. K₃[AlF₆] Key idea: AlF₃ is covalent and insoluble; extra F^- from KF forms a soluble complex. AlF₃+3KF→ K₃[AlF₆] The stable hexaf... 1