Q4 of 48 Page 2

(a) Write the che

(a) Chemical name washing soda: Sodium carbonate decahydrate chemical formula of washing soda: Na2CO3.10H2O

(b) Washing soda produce by Solvay process by the reaction ammonical brine with CO2 gas


NaCl + NH3 + CO2 + H2O NaHCO3 + NH4Cl


NaHCO3 on heating produces Na2CO3 (soda ash) which on recrystallization produces washing soda




(c) Washing soda is a basic salt because it is a salt of a strong base (NaOH) and weak acid (H2CO3) with pH value more than 7.


Use: Washing soda is used for softening hard water.


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24

In the following schematic diagram for the preparation of hydrogen gas as shown in the given figure, what would happen if the following changes are made?


(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.


(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.


(c) In place of zinc, copper turnings are taken.


(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated. ( CBSE 2005)

 25

(a) Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this slat. Name the source from where it is obtained.

(b) What is rock salt? Mention its colour and the reason due to which it has this colour.


(c) What happens when electricity is passed through brine? Write the chemical equation for it. ( CBSE 2007)

 5

Write the chemica 6

(a) Identify the