Gamma rays are photons with very high energy. How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1 10-13 J? (h = 6.626 10-34 J s, c = 3.00 108 m/s)
A) 1.0 106
B) 1.4 108
C) 6.2 109
D) 3.9 103
Question 2
Two experimental runs are performed to determine the calorimetric properties of an alcohol that has a melting point of -10C.
In the first run, a 200-g cube of frozen alcohol, at the melting point, is added to 300 g of water at 20C in a styrofoam container. When thermal equilibrium is reached, the alcohol-water solution is at a temperature of 5.0C. In the second run, an identical cube of alcohol is added to 500 g of water at 20C and the temperature at thermal equilibrium is 10C. The specific heat of water is 4190 J/kgK. Assume that no heat is exchanged with the styrofoam container and with the surroundings. The heat of fusion of the alcohol is closest to
A) 5.5 104 J/kg
B) 7.1 104 J/kg
C) 7.9 104 J/kg
D) 6.3 104 J/kg
E) 8.7 104 J/kg
Why leaves are green: interaction of light with chloroplasts.
(A) Scratch test; patient is exposed to allergens through a light scratch on the skin; (B) Positive
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