Gas $\mathrm{A}$ is formed when granulated Zinc reacts with dilute Hydrochloric Acid. It reacts with Oxide $\mathrm{B}$ and reduces it to Copper metal. Write the names of $\mathrm{A}$ and $\mathrm{B}$ and also give the equations for the described reaction.

Sevati took Sulphur powder in a deflagrating spoon, heated it and collected the gas formed in a test tube. What will happen when moist red and blue litmus papers are taken near the mouth of the test tube and why? Write the chemical equations for the reactions taking place.

The process described below are due to which property of Hydrogen - 

A Hydrogen filled balloon floats in the air.

The process described below are due to which property of Hydrogen -

A 'pop' sound is heard when lighted match stick is taken near the mouth of the Hydrogen filled gas jar.