Wednesday 14 May 2014

CH. 2 ACIDS, BASES AND SALTS

1.    Name the acid present in lemon juice, milk, bee sting
Ans: citric acid, lactic acid, methanoic acid
2.    What name is given to an indicator which gives different odour in different medium?
Ans: Olfactory indicator
3.    How will you test with litmus paper that the given solution is acidic or basic?
Ans: an acidic solution turns blue litmus red whereas a basic solution turns red litmus blue.
4.    Give one example each of a strong acid and weak acid.
Ans: strong acid : Hydrochloric acid
Weak acid: acetic acid
5.    Name the indicator which can  give us an idea of how strong or weak an acid or base is.
Ans: Universal indicator
6.    Name the substance obtained by the action of chlorine on dry slaked lime.
Ans : Bleaching powder
7.    Which has a higher pH value, conc. HCl or dil. HCl?
Ans: Dil. HCl, because it has less amount of H+ ions.
8.    Name the from lichens acid base indicator extracted
Ans: Litmus
9.    Name the sodium compound which is used for softening hard water.
Ans: Sodium carbonate
10.          Name the acid present in our stomach that helps in digestion.
Ans: Dil. HCl
11.          What is the ideal pH of the soil for the healthy growth of a plant?
Ans: for the healthy growth of the plant the pH of the soil should be neither too alkaline not highly acidic.
12.           Name the mild base used to reduce acidity in the stomach.
Ans: Antacids e.g. Magnesium hydroxide
13.          What is the pH of rain water that leads to acid rain?
Ans: when pH of rain water is less than 5.6, it is called acid rain.
14.           What is the effect of dilution of H+ ion concentration of an acid.
Ans: On dilution of an acid solution, the concentration of H+ ion
Decreases per unit volume.
15.          A chemical substance is used to set the fractured bones in the right position. Give the chemical name and formula of this substance.
Ans: Plaster of Paris. The chemical name of the compound is calcium sulphate hemihydrate.
Formula is CaSO4. ½ H2O.

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