26. your mother will soon undergo some medical testing that will require her to swallow a radioactive

isotope as a tracer. she is nervous about having a radioactive substance in her body even though the

radiologist told her not to worry, as the isotope has a half-life of only 7 minutes. explain to her what

a half-life is, and the significance of the half-life being 7 minutes.

Figure 10-1 study figure 10-1. the strong nuclear force felt by a single proton in a large nucleus

Use the table to identify the phase and phase changes of the elements under the given conditions. write the name of the substance, phase, or phase change. when the temperature in a room increases from 25°c to 33°c, changes from a solid to a liquid. in a lab, methane and nitrogen are cooled from -170°c to -200°c. the methane freezes and the nitrogen . when gold is heated to 2,856°c it changes from a liquid to a .

The following reaction shows sodium carbonate reacting with calcium hydroxide. na2co3 + ca(oh)2 → naoh + caco3 how many grams of naoh are produced from 20.0 grams of na2co3? (molar mass of na = 22.989 g/mol, c = 12.01 g/mol, o = 15.999 g/mol, ca = 40.078 g/mol, h = 1.008 g/mol) 12.2 grams 15.1 grams 24.4 grams 30.2 grams