CBSE ADDA

Solved questions for Exam Q.1 Why is carbon tetravalent? Ans 1: Carbon atom has 4 electrons in the outermost shell.It needs 4 more electrons to complete its octet. Therefore, carbon is tetravalent . Q.2 The formula of a hydrocarbon is Cn H2n. Name the family to which it belongs and also predicts its nature. Ans 2: The hydrocarbon belongs to alkenes It is unsaturated in nature. Q.3 What is the valency of carbon in CH3-CH3, CH2=CH2 and HC=CH ? Ans 3: The valency of carbon in all its compounds whether saturated or unsaturated is 4. Q.4 Out of butter and ground nut oil , which is unsaturated in Nature? Ans 4: Groundnut oil is unsaturated in nature . Q.5 Why is high temperature not favourable for alcoholic fermentation? Ans 5: The high temperature destroys the enzymes which are needed to carry fermentation . Q.6 Name a cyclic unsaturated hydrocarbon, containing three double bonds? Ans 6: Benzene Q.7 What is the difference in the molecular mass

Q. Is shampoo acidic or basic?  Shampoo is generally made by the salts of a weak acid and a strong base, so they're somewhat basic. Shampoos usually are at pH 5.5 because at slightly acidic pH the scales on a hair follicle lay flat making the hair feel smooth and look shiny. Citric acid is used to adjust the pH down to 5.5 (is). It is a fairly weak acid which makes the adjustment easier. Q. Why government has put ban on the sale of shahtoosh shawls? Shahtoosh shawl, made from the wool of endangered Tibetan antelope, Chiru which is a rare animal Therefore, government has put ban on the sale of shahtoosh shawls for the purpose of conservation and protection Q. Why is sericulture not considered on eco-friendly practise? Sericulture not considered on eco-friendly practice because during sericulture silk worm is boiled to get silk fibres. Vapours emitted from the boiling cocoon release toxic fumes that pollute the atmosphere contribute to respiratory problem. Q. Why is sh

Chemistry x - OXIDATION AND REDUCTION Oxidation:  A chemical reaction which involves  addition of oxygen or removal of hydrogen or loss of electron(s)  is called as oxidation. 2Mg + O2 →2MgO (addition of oxygen) H2S + Br2 → 2HBr + S (removal of hydrogen) Fe2+ → Fe3+ + e- (loss of electron) Reduction : A chemical reaction which involves  addition of hydrogen or removal of oxygen or gain of electron(s)  is called as reduction. 2Na + H2 → 2NaH (addition of hydrogen) CuO + H2 → Cu + H2O(removal of oxygen) Fe3+ + e- → Fe2+ (gain of electron) Redox reaction:  A chemical reaction in which  oxidation and reduction  take place  simultaneously  is called redox reaction. Zn + CuSO4 → Cu + ZnSO4 ZnO + C → Zn +CO MnO2 + HCl → MnCl2 + H2 O + Cl2  OXIDATION AND REDUCTION Ch. Chemical and chemical   Equations In our daily life we come across phenomena like fading of the colours of the  clothes,  burning of combustible substances like cooking gas, wood and coal, and also r