c2.2 p30 PRACTICE! Determine which of the following names are valid identifiers. If a name is not a valid identifier, give the reason that it is not acceptable, and suggest a valid replacement. 1: density 2: area 3: Time 4: xsum 5: x_sum 6: tax-rate 7: perimeter 8: sec^2 9: degrees_C 10: break 11: #123 12: x&y 13: count 14: void 15: f(x) 16: f2 17: Final_Value 18: w1.1 19: reference1 20: reference_1 21: m/s c2.2 p31 PRACTICE! In Problems 1 through 6, express the value in scientific notation. 1. 35.004 2. 0.00042 3. -50,000 4. 3.15723 5. -0.0999 6. 10,000,002.8 In Problems 7 through 12, express the value in floating-point notation. 7. 1.03e-5 8. -1.05e5 9. -3.552e6 10. 6.67e-4 11. 9.0e-2 12. -2.2e-2 c2.2 p35 PRACTICE! Give the preprocessor directives to assign symbolic constants for these constants: 1: Speed of light, c = 2.99792 x 108 m/s 2: Charge of an electron, e = 1.602177 x 10-19 C 3: Avogadro's number, N_A = 6.022 x 1023 mol-1 4: Acceleration of gravity, g = 9.8 m/s2 5: Acceleration of gravity, g = 32 ft/s2 6: Mass of the Earth, M_E = 5.98 x 1024 kg 7: Radius of the Moon, r = 1.74 x 106 m 8: Unit of length, Unit_Length = 'm' 9: Unit of time, Unit_Time = 's'