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Winter vacation home work for class XI(2013-14) Subject: - Chemistry 1. 2. 3. 4. 5. Why are halides of beryllium polymeric? Desrive the importance of (i) Lime stone (ii) cement (iii) plaster of paris. Descrive two similarities and differences between B and Al. Suggest a reason as to why CO is poisonous. Explain the formation of (i) Water gas (ii) Producer Gas. Give their uses. What happens when CO2 is passed through lime water (i) for short duration (ii) For long duration? 6. Give reasons for the following observations : (i) KO2 is paramagnetic in nature. (ii) A solution of Na2CO3 is alkaline. (iii) LiI is more soluble than KI in ethanol. (iv) BaO is soluble but BaSO4 is insoluble in water. (v) BeO is almost insoluble but BeSO4 is soluble in water. (vi)Li does not form alum like other alkali metals. (vii) Among all the alkali metals Lithium is the strongest and Sodium is the weakest reducing agent. (viii)Boric acid considered as weak monobasic acid. (ix) Graphite is used as lubricant. (x) Diamond is used as an abrasive. 7. What are silicones? Give two uses of silicones. 8. Write balance chemical equations for: (i) B2H6 + NH3→ (ii) Al + NaOH → (iii) Al + HCl → (iv) SiO2 + HF → (v) Na2O2 + H2O → (vi) AlN + H2O → (vii) B2O3 + H2O → (viii) Al4C3 + H2O → (ix) Mg + Liq. NH3 → (x) CaO + SiO2 → 9. Arrange the following in the property mentioned : (i) Li+ , Na+ , K+, Rb+, Cs+ (increasing order of mobility in water) (ii) Be+ +,Mg+ +, Ca+ +, Sr+ +,Ba++(increasing order of hydration enthalpy) (iii) B2O3,In2O3, Ga2O3 ,Al2O3 (increasing order of basic nature) (iv) Ge ,Sn ,Pb (increasing order oxidizing power of tetravalent species) (v) PbF2, PbCl2 ,PbBr2, PbI2(increasing order ionic character) (vi) InCl3, BCl3, GaCl3, AlCl3 (increasing order of acidic nature) 10. Compare the solubility and thermal stability of the following compounds of alkaline earth metals with those of the alkaline earth metals (i) Nitrates (ii) Carbonates (iii) Sulphates. 11. Explain structures of boric acid, diborane and Al2Cl6. 12. Potassium carbonate cannot be prepared by Solvay’s process. Why?