naturally occurring iodine has an atomic mass of 126.9045. a 12.3849-g sample of iodine is accidentally contaminated with 1.00070 g of 129i, a synthetic radioisotope of iodine used in the treatment of certain diseases of the thyroid gland. the mass of 129i is 128.9050 amu.

How is 0.00235 expressed in proper scientific notation? a. 2.35 × 10-3 b. 0.235 × 10-2 c. 2.35 d. 2.35 × 103

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

The number at the end of an isotope’s name is the number.