40 POINTS..... Plz answer fast .Don't spam.I will mark best answer as brainliest.ans qn no 8 to qn no.11
Answers
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Here Is Your Answer:
8. *(i) Tap water contains dissolved salts in it. These salts dissociates into ions when electricity passed through it which are responsible for the electricity conductivity of tap water. But distilled water does not contain any dissolved salts, so it does not conduct electricity.
*(ii) This is because gaseous HCl does not dissociate to give up protons and chloride ions. But, in aqueous solutions HCl does dissociate and exist in ionic form:
H2O(l)+HCl(aq)⟶H3O+(aq)+Cl−(aq)HX2O(l)+HCl(aq)⟶HX3OX+(aq)+ClX−(aq)
Thus it acts as a typical Bronsted acid (proton donor) in an aqueous environment. In this case, water is gaining a proton (H+)(HX+), so it is a base, while HCl is giving one away, so it is an acid.
Therefore it is able to turn the blue litmus paper red (a behaviour typical of acids).
*(iii) During summers the temperature is high Lactobacillus increases which converts into lactic acid decreasing the pH of milk. Chance the milkman usually adds a very small amount of baking soda to fresh milk to increase the pH of the solution as it is a base and neutralise the milk in summers.
*(iv) Because If we add water to acid , this reaction would become highly exothermic and lits of heat would be generated which would split on your face and cause severe burns, Therefore it us told while diluting an acid always acud should be added to the water.
*(v) Ammonia instead of not having hydroxyl group is a base because it forms OH- ions when added to water as it ionises to form ammonium ions and hydroxide ions after forming ammonium hydroxide when mixed in water.
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9. (a) Hydrated copper sulphate – CuSO4.5H2O Anhydrous copper sulphate – CuSO4. Activity :
(i) Heat a few crystals of copper sulphate in a dry boiling tube.
(ii) Add 2-3 drops of water on the sample of copper sulphate obtained after heating. After heating, water is removed and salt turns white. If crystal are moisten again with water, blue colour reappears. Water of crystallization is fixed number of water molecules present in one formulae unit of a salt. Five water molecules are present in one formula unit of copper sulphate. *Calcium sulphate hemihydrate – CaSO4. H2O Calcium sulphate dihydrate – CaSO4.2H2O.
*(b) Chemical name and Chemical Formula
The chemical name of plaster of Paris is calcium sulphate hemihydrate because half molecule of water is attached with calcium sulphate. The chemical formula of plaster of Paris is CaSO4.1/2H2O.
CaSO4 . 1/2H2O + 3/2H2O ----> CaSO4 . 2H2O
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*10. Baking soda is a chemical compound which is also called as - Sodium bicarbonate (NaHCO₃).
(i) Antacid - NaHCO₃ acts like an absorbable antacid. Baking soda imitates the action of natural sodium bicarbonate in the body and neutralizes the stomach acid relieving acid reflux.
(ii) Soda-acid fire extinguisher - A soda-acid fire extinguisher is usually a mixture of baking soda and an acid which is commonly sulfuric acid. It is used as a pressurized expeller to put off the fire. When it is expelled, a reaction in between the contents of the soda-acid occurs which releases carbon dioxide that extinguishes the fire.
(iii) Baking - When baking soda is mixed with moisture and with an acidic substance like yogurt, buttermilk etc, a chemical reaction occurs which produces carbon dioxide gas as bubbles. These bubbles expand under hot temperatures like in the oven while it is baking. This causes the baked bread or cake to become soft and spongy.
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*11. Solution A is strong basic in nature
Solution B is acidic in nature
Solution C is to be nuetral.
Solution D is strong acidic in nature.
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Answer:
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