Approximately what precent of parent isotopes remains after 0.5 half lives have passed

Amass of 100.0 g of solute is dissolved in water so that 850. ml of a 0.7500 m solution has been prepared. what is the molar mass of the solute?

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

Ageochemist examines a piece of metal that he found in the soil. he performs tests to identify the metal from its density, electrical conductivity, and melting point. which statement best describes his investigation? a. he is determining physical properties that are sufficient to identify the metal. b. he is determining chemical properties that are sufficient to identify the metal. c. he is determining physical properties that are insufficient to identify the metal. d. he is determining chemical properties that are insufficient to identify the metal.