(1) substances are composed of molecules; Molecules never stop moving irregularly. The molecules of concentrated ammonia never stop moving irregularly and will volatilize and escape ammonia. Therefore, concentrated ammonia water should be sealed to prevent ammonia molecules from moving and spreading.

(2) The main component of firewood is C, which reacts with oxygen to generate carbon dioxide gas, and the gas escapes, so the mass of ash is smaller than that of firewood;

(3) Diamond, graphite and C 60 are all allotropes of carbon, and their carbon atoms are arranged in different ways, so each has its own appearance, density and melting point.

(4) The outermost layer of 4)Cl has seven electrons. In chemical reactions, it is easy to get an electron to form a stable structure, thus forming a negatively charged ion, namely Cl-, so their properties are different;

(5) As shown in the figure, the sign indicates that smoking is prohibited; Because there are suspended particles in the air of gas stations and flour mills, which are easy to burn, smoking is strictly prohibited in these places.

So the answer is: (1) stop the movement and diffusion of ammonia molecules;

(2) The firewood reacts with oxygen to generate carbon dioxide gas to escape, so the quality of ash is smaller than that of firewood;

(3) Their carbon atoms are arranged in different ways;

(4) The number of electrons in the outermost layer is different;

(5) No smoking; Gas stations, flour mills, etc.