2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.
OR
The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses.
2ml of sodium hydroxide reacts with zinc metal to give a gas. The gas formed is Hydrogen (H2) and the compound formed is sodium zincate. The reaction is
To test the presence of the gas, bring the mouth of the test tube near a burning matchstick. If the flame extinguishes with a ‘pop’ sound, then the presence of Hydrogen gas is confirmed.
When Zn reacts with dilute solution of a strong acid, H2 gas will be evolved.
Example: 
OR
The salt used is sodium bicarbonate or sodium hydrogen carbonate. Its chemical formula is NaHCO3.
Sodium hydrogen carbonate can be formed by using NaCl as a base raw material. The reaction is given as:
NaHCO3 is used -
(i)- In soda-acid fire extinguishers.
(ii)- as an ingredient in antacids.
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