1. One section of a steel railroad track is 25 meters long, if its temperature increases by 40 K during the day, how long does the track expand? The coefficient of linear thermal expansion of steel   12 106 per Kelvin

a. 12×10^6m

b. 12×10^4m

c. 12×10^3m

d. 1.2m 

2. Approximately how many moles of gas molecules are in the classroom

1. 5×10^4moles
2. 2×10^moles
3. 9×10^3moles
4. 1×10^3 moles