EASY
7th CBSE
IMPORTANT
Earn 100

When a soda water bottle is opened, a gas is released. Does a chemical reaction occur? Explain.
 

Important Questions on Physical and Chemical Changes

MEDIUM
7th CBSE
IMPORTANT
Living Science 7>Chapter 8 - Physical and Chemical Changes>EXERCISES>Q 5
Why should we not put stainless steel spoons in pickle jars?
 
HARD
7th CBSE
IMPORTANT
Living Science 7>Chapter 8 - Physical and Chemical Changes>EXERCISES>BE A SCIENTIST
Meeta's mother complained that white deposits form on all her utensils used for cooking. Meeta knows that the deposits are of calcium carbonate that gets left behind when water in the utensils evaporates. She also knows that calcium carbonate reacts with hydrochloric acid. However, she realises that hydrochloric acid is not easily available and is too dangerous for her to use in the kitchen to remove the stains.
Suggest to Meeta a method that uses the same principle as she thought of, but solves the two problems she has with hydrochloric acid.