Acid Bases and Salts 

CBSE extra question 

class 10



ONE MARK QUESTIONS


1. Three acidic solutions A, B and C have pH = 0, 3 and 5 respectively.
Which solution has the highest concentration of H ions?
Which solution has the lowest concentration of H ions?            [CBSE 2015]             
Ans : 
a. The solution with pH = 0 has highest concentration
of H ions.
b. The solution with pH = 5 has lowest concentration of H ions.

2. What is meant by p and H in pH? 
Ans : p stands for ‘potenz’in German meaning power, H stands of hydrogen.

3. Define alkalies and give an example.
Ans : Water soluble bases are called alkalies e.g., NaOH

4. Mention the range of pH for identification of a base
Ans : 7.1 to 14 is the pH range for bases.

5. How chloride of lime differs from calcium chloride?
Ans : CaOCl is the chloride of lime whereas CaCl calcium chloride.

6.What is meant by water of crystallisation in a substance?
The water molecules associated with a crystalline solid are called water of crystallisation.

7.At what pH rain water is said to be acidic ?
When pH < 5.5, the rain water becomes acidic.

8.Which among distilled water, tap water and sea water is the best conductor of electricity?
Sea water is a better conductor due to the presence of ions.

9.Name the acids present in (i) nettle sting, (ii) curd.
HCOOH, Formic acid,
Lactic acid, CH3-CH(OH)-COOH

10.Why is HCl a stronger acid than acetic acid?
HCl is completely ionised in aqueous solution whereas acetic acid is only partially ionised in aqueous solution.

11.Name a salt which does not contain water of crystallisation.
NaHCO is a salt that does not contain water of crystallisation.


12.Write the name and chemical formula of the product formed by heating gypsum at 373 K
                                                                                                                         [CBSE 2010]
Plaster of Paris, CaSO

13.Name the chemicals used in acid fire extinguisher and the gas evolved from it when it is used?
 NaHCO (Sodium hydrogen carbonate) and H SO (Sulphuric acid). The gas evolved is carbon dioxide. 

14.Which is a stronger acid, with pH = 5 or with pH=2?
The acid with pH = 2 is a stronger acid.

15.The pH of a sample of vegetable soup was found to be 6.5. How is this soup likely to taste?
It will be sour in taste.

16. Which bases are called alkalies? Give one example of alkali.
Those bases which are soluble in water are called alkalies e.g., NaOH, KOH.

17.A compound which is prepared from gypsum has the property of hardening when mixed with a proper quantity of water. Identify the compound and write its chemical formula.
CaSO4. 2 H2O (Plaster of Paris), Calcium sulphate hemihydrate

18.What is meant by term pH of solution? The pH of rain water collected from two cities A’and ‘B’were found to be 6.0 and 5.0 respectively. The water of which city will be more acidic?
 It determines the strength of acid and base. Rainwater with pH = 5 is more acidic.

19.A few drops of sulphuric acid are added to water before electrolysis, why?
Water is not a good conductor of electricity. Few drops of sulphuric acid makes it better conductor of  electricity

20.Suggest one way to reduce alkaline nature of the soil.
Add ammonium nitrate (Acidic salt) to neutralise alkaline nature of soil.