11.   The color of a star depends on its chemical composition and its Mass.

12.   The fourth question with which I started this chapter concerns the maintenance of a different chemical composition in different places.

13.   The nostrils open into cups which can detect the most minute changes in the chemical composition of water.

14.   ...the chemical composition of the ocean.

15.   During chemical reactions, one or more substances change their chemical composition to form one or more new substances.

16.   More importantly, they do not provide information about the chemical composition of the substance.

17.   The boundary between the mantle and crust represents a significant change in rock density but there may also be differences in chemical composition.

18.   The character of the ensuing volcanism is largely a function of the viscosity of the magma which is, in turn, dependent on its chemical composition and temperature.

19.   The air samples could give scientists vital information about long-term changes in the chemical composition of the atmosphere.

20.   Analysis of the lines allows scientists to calculate the chemical composition of distant celestial objects.