The area of a telescope lens is 6.679 × 103 mm2. (a) what is the area in square feet (ft2)? enter your answer in scientific notation. (b) if it takes a technician 43.4 s to polish 1.46 × 102 mm2, how long does it take her to polish the entire lens?

Given:

Area of a telescope lens = 6.679 *

a)

Area of lens = 6.679 * * 1.076*10^{-5} ft^{2}[/tex]

                     = 7.187 *

b) Time taken to polish an area of 1.46 * = 43.4 s

Therefore, time taken to polish the entire lens

                   = 43.4 * 6.679 *

                   = 1985 sec  

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles