An expensive vacuum system can achieve a pressure as low as 1.00 × 10 − 10 N / m 2 at 25.5 °C . How many atoms are there in a cubic centimeter at this pressure and temperature?

The brightest star in the night sky in the northern hemisphere is sirius. its distance from earth is estimated to be 8.7 light years. a light year is the distance light travels in one year. light travels at a speed of 3.00 × 108 m/s. calculate the distance from earth to sirius in miles. (1 mi = 5280 ft) g