Chemical bonds
a. are always ionic.
b. combine compounds to form elements.
c. are always covalent.
d. hold atoms together to form compounds.

. a pyramid of numbers differs from an ecological pyramid because it
a. shows the amount of energy within each trophic level.
b. displays the number of organisms at each trophic level.
c. is organized by trophic levels, while an ecological pyramid isn't.
d. attempts to describe a food chain or food web.

A100 kmol/h stream that is 97 mole% carbon tetrachloride (ccl4) and 3% carbon disulfide (cs2) is to be recovered from the bottom of a distillation column. the feed to the column is 16 mole% cs2 and 84% ccl4, and 2% of the ccl4 entering the column is contained in the overhead stream leaving the top of the column. calculate the mass and mole fractions of ccl4 in the overhead stream, and determine the molar flow rates of ccl4 and cs2 in the overhead and feed streams. 12. mw_ccla- 153.82; mw_cs2-76.14.