Is calcium carbonate a compound element or mixture?

Which statement names the physical property of wood a. wood is softer than coal b. wood does not rust c. wood can rot d. wood can burn

For questions 1 and 2, consider the following experimental data.hydrogen emission lines were detected at the following wavelengths (in nm): 121.6102.697.395.093.8question 1use the electromagnetic radiation classifications below and figure 1-1 in the introductory information for this lab (in the lab manual) to determine the nf value for the experimental data provided? wavelength, ? (nm) 650 700 550 600 400 450 500 visible spectrum wavelength, ? (m) 11 10 3 10 10 10 8 10 5 10 10 -10 10 9 10 10 10 10 -12 10 microwave radio infrared x-ray ultraviolet gamma 1020 1019 1018 1 1016 015 1014 01 12 109108 frequency, v (hz)a.1b. 2c. 3d. 4e. 5question 2using the data for the emission line with the longest wavelength, the known value of nf (from question 1 in this prelab), and the value of ni (deduced from the ? and nf values) calculate the rydberg constant for hydrogen (rh) in units of m-1.a) 1.097 x 10-11 m-1b) 5.921 x 107 m-1c) 1.097 x 10-2 m-1d) 9.252 x 106 m-1e) 1.097 x 107 m-1

An engineer decides to use a slightly weaker material rather than a stronger material, since she knows that the stronger material can break suddenly. this is an example of what? a choosing a material that will show warning before it fails b using composite materials that combine strength c using a material for multiple applications d using design techniques that increase efficiency and reduce cost