Today we cannot imagine a world without antibiotics.
Define antibiotics?

Today we cannot imagine a world without antibiotics. Name the first antibiotic to be discovered.

A broad specturm antibiotic is

Nobody can Imagine a world without sound. Sound is a part of our life- musics, ripples, echoes etc. have a lot of applications.Doctors use an ultrasonic scanner to diagnose tumour tissues. If the frequency of the scanner is locate 4.2MHz and the speed of sound wave in the tissue of is 1.7 kms find the wavelength of the sound wave.

Nobody can Imagine a world without sound. Sound is a part of our life- musics, ripples, echoes etc. have a lot of applications. Can you say how a bat can ascertain directions and distances without any 'eyes'?

Which of the following is an antibiotic?