Calculate the formula mass of Aluminium oxide, ${\mathrm{Al}}_2{\mathrm{O}}_3$.

It was diagnosed that the body of a patient has lost its power of fighting any infection. Name the disease he is suffering from. What type of microbe is responsible for this disease and how does it spread from one person to other.

"Forests influence the quality of our air, soil and water resources." Justify the statement.

Define green revolution. What are the common objectives of crop improvement?

When an incense stick (agarbatti) is lighted in one corner of a room, its fragrance quickly spreads in the entire room. Name the process involved in this.