Answer:
Mechanical waves are waves that require a medium. This means that they have to have some sort of matter to travel through. These waves travel when molecules in the medium collide with each other passing on energy. One example of a mechanical wave is sound.
Answer:
C) 100 joules
Explanation:
The kinetic energy of an object is given by:

where m is the mass of the object and v its speed.
In this problem, we have an object of mass m = 50 kg and v = 2 m/s, so by using the formula we can find its kinetic energy:

Answer:
The lone pair of electrons occupy more space because the electrostatic force becomes weaker.
Explanation:
When there is a bond pair of electrons in the 2 positively charged the atomic nuclei draw the electron density towards them, thereby reducing the bond diameter.
In the case of the lone pair, only 1 nucleus is present, and the enticing electrostatic force becomes weaker and the intensity of the electrons will be increases. Therefore, the lone pair occupies more space than the pair of bonds.
What substances? Depends on their density, the lower density floats on top. For example, oil floats on top of water