Answer:
A. The melting of ice is both a desirable and undesirable change because, ice is needed to melt so as to make liquid water available for animal and plant use and consumption and also to release the energy used in the fusion process of ice formation. Melting of ice is undesirable because melting ice liberate water slowly, and the water liberated can erode surface soil. Melting ice reduces the available heat sink on earth and also reduces the available stored up fresh water supply on earth.
B. The appearance of hailey comet once every 72 year is a periodic change because it's motion around the solar system is repeated with time. The reason for this highly elliptical and eccentric path of motion is largely due to the gravitational effect of the sun and the planets on the comet.
Answer:
D, rubber
Explanation:
Metals have free electrons, and are very bad as insultators. Metals conduct electricity very well. On the other hand, rubber has no free electrons and does not conduct electricity very well
At the release point, the ball has kinetic energy,
and at its maximum height it has potential and kinetic energy,
where 
is the maximum height attained above the release point.
The LoCoE tells us that we should have
Density is the mass divided by the volume
