What is the color of a potassium dichromate solution?

Which gas is useful for inhibiting bacterial growth?

What is the difference between displacement and double displacement reactions? Write equations for these reactions.

When air is blown from the mouth into a test tube containing lime water,the lime water turns milky due to the presence of:

The following diagram displays a chemical reaction. Observe it carefully and answer the following questions:
$(a)$ Identify the type of chemical reaction that will take place and define it. How will the colour of the salt change?
$(b)$ Write the chemical equation of the reaction that takes place.
$(c)$ Mention one commercial use of this salt.

Give the characteristic tests for the following gases:
$(a)$ $CO_2$
$(b)$ $SO_2$