Why sewage disposal into natural bodies is not advised?

Why mule is sterile in nature?

Why are rain drop spherical in nature?

How are medical wastes disposed?

Why B_(2) is paramagnetic in nature while C_(2) is not?

Dr. Usha is a pulmonologist (Doctor for respiratory diseases). One day , a school student named Arjun , met her with respiratory problems. After diagnosis , the doctor advised him to go playground daily and play football or basketball. She also advised to do pranayamam in the morning. Why did the doctor advised him to go to the playground ?

_________ stated that the natural state of all Earthly bodies is at rest .