If a radiographic substance's half-life is 20 years, how much of a 40 gram sample will be left after 60 years?
A. 5 grams
B. 10 grams
C. 20 grams
D. 30 grams

What is one difference between austria and switzerland? a. austria is landlocked. b. austria has more minerals resources c. austria has a strong tourism industry d. austria has a strong dairy cattle industry

Compared with the land in the highlands, the lowlands region of england a) rockier and more difficult for farmingb) the center of business and industryc)richer in coal reservesd)covered by more fertile farmland d) covered by more fertile farmland

Select the correct answer.look at this nineteenth-century illustration of london. which explanation best relates this illustration to changes in britain in the 1800s? a.factory workers in cities lost their livelihood because of the lack of housingb.industrialization narrowed the inccome gap between landowners and workers.c.the migration of workers from rural to urban areas resulted in overcrowded citiesd.the spread of railways allowed farmers to sell produce far from where it was grown.