Which of the following statements are true for first-order analyses of nmr spectra (the type of analysis most commonly done). 1. carbon-13, an nmr-active nucleus, has a nuclear spin quantum number of 0. 2. the peak multiplicity in a proton spectrum is (n+1), where n is the number of adjacent, equivalent hydrogens. 3. first-order multiplets are symmetrical, and their chemical shift is given by the position of the first peak in the multiplet. 4. the spin-multiplicity of the proton nmr absorption of the methyl group in ethanol-od is 4. 5. the difference in absorption frequency is equal to or less than 6 j. 6. the peak multiplicity in a proton spectrum is (n+1), where n is the number of adjacent, equivalent hydrogens.