The distance between an object and a screen is 200 cm. When a lens is placed in between the object and the screen, an image which is real and the same size as the object is formed on the screen. Which lense is used ?​

Sounds propagates through some kind of medium. usually it's air, but it goes just as well through solid objects like walls, windows etc. a soundwave will compress the (air)molecules in front of it, and if this increased density wave hits your ears, you register it as sound. solid objects like walls are a lot denser than air, this means that they will damp a wave, but also carry it easier.

Ceardrum passes to the cichela which then send it tovthe auditory nerve until youvhear it fullu