. A student is conducting an investigation to determine the identity of an unknown substance. The following data were collected: 1. The substance is yellow 2. The substance melts at 273 degrees Celsius 3. When placed in water the substance floats. 4. When in the presecne of a flame, the substance does not burn. 5. When the substance is addred to hydrochloric acid, a gas forms and a temperature change occurs. Which of these observations represents physical properties of the substance? A. 1, 2, 3 B. 1, 3, 5 C. 1, 2, 4 D. 3, 4, 5

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Effect of rotenone and antimycin a on electron transfer rotenone, a toxic natural product from plants, strongly inhibits nadh dehydrogenase of insect and fish mitochondria. antimycin a, a toxic antibiotic, strongly inhibits the oxidation of ubiquinol. (a) explain why rotenone ingestion is lethal to some insect and fish species. (b) explain why antimycin a is a poison. (c) given that rotenone and antimycin a are equally effective in blocking their respective sites in the electron-transfer chain, which would be a more potent poison? explain.

The molality of calcium chloride (cacl2) in an aqueous solution is 2.46 m. what is mole fraction of the solute?