Because the melting/freezing point is the point at which the particles in a substance begin to go through the phase change
so for example at 0 degree's Celsius water starts to freeze, but at the same time also melts, its sorta like some of the particles are freezing while the others are melting at the same time, but if you go above 0 degrees then it melts, and if you go below it freezes
The answer is D. This means that is you have a determined amount of force (in newtons) being applied on an object of known mass (in kilograms), then to determine the acceleration of the object, divide the force by the mass (or multiplying the force with the inverse of the mass of the object). This behavior of objects is stipulated in Newtons/ second law. Increasing the force increases the acceleration while increasing the mass decreases the acceleration of the object. Acceleration is a vector quantity meaning it has magnitude and direction.
Having two copies of the mutated genes cause sickle cell anemia, but having just one copy does not, and can actually protect against malaria - an example of how mutations are sometimes beneficial.
The majority of mutations have neither negative nor positive effects on the organism in which they occur. These mutations are called neutral mutations. Examples include silent point mutations. They are neutral because they do not change the amino acids in the proteins they encode.
Hope this helped :)
