Mechanical waves don't require a medium. True. Mechanical waves are able to travel through air, water and solids.
It depends on the type of mechanical wave.
False. Mechanical waves cannot travel through a vacuum.
True, but only medium mechanical waves need a medium.

False. Mechanical waves cannot travel through a vacuum.

Explanation:Type of wave that can travel through the vacuum of space - DOES NOT require a medium. ... False: A vacuum is empty space (no matter). Sound waves must have a medium (matter) in order to travel. Sound waves are mechanical waves.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

there is none because earth is stationary and flat.