I thank that your answer is C.
Electrons in an atom are found on different electron shells depending on how much energy they possess, and they determine how atoms will interact with each other. The outermost electron shell holds the valance electrons.
The answer is D because there is no forces of attraction or repulsion between gas particles .
It is a trial aimed to reduce bias during an experiment. An example would be a sugar pill, something that has no real effect so that the results of the true trial can accurately be compared. Its like a control group.
A physical change is a change to a sample of matter in which some properties of the material change, but the identity of the matter does not. Physical changes can further be classified as reversible or irreversible. The melted ice cube may be refrozen, so melting is a reversible physical change.
