A. Adsorption chromatography
B. Ascending chromatography
C. Radial chromatography
D. Descending chromatography
A. crushing heating mixing grinding
B. crushing mixing heating grinding and mixing
C. crushing grinding mixing heating
D. mixing heating grinding crushing
A. 40.7 KJ/mole
B. 40.7 J/mole
C. 40.7 cal/mole
D. 40.7 Kcal/mole
A. Rayleigh
B. Ramsay
C. Lockerey
D. Dalton
A. Two
B. Three
C. Four
D. Six
A. Flurocarbon
B. Carbon monoxide
C. Methane
D. C2H2
Which of the following is a substance?
A. Sea water
B. Brass
C. Tape water
D. Graphite
E. Sand
In chemistry, a substance refers to a matter which has specific composition and specific properties which do not change. A substance can be an element or a compound. A substance typically has a constant composition, which can not be separated by physical methods. Seawater and sand are not substances, because they have varied compositions and their components can be separated by physical methods.