Calculate the mass percent of a solution prepared by dissolving 17.2 g of NaCl in 149 g of water

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

The atomic radius of sodium is 186 pm and of chlorine is 100 pm. the ionic radius for na+ is 102 pm and for cl– is 181 pm. in going from na to cl in period 3, why does the atomic radius decrease while the ionic radius increases? a. the inner electrons in the sodium cation shield its valence electrons more effectively than the inner electrons in the chloride anion do. b. the inner electrons shield the valence electrons more effectively in the chlorine atom than in the chloride anion. c. the outermost electrons in chloride experience a smaller effective nuclear charge than those in the sodium cation do. d. the outermost electrons in chloride experience a larger effective nuclear charge than those in the sodium cation do. e. monatomic ions are bigger than the atoms from which they are formed.

Ineed this asap part i: scientific method what is the difference between science and pseudoscience? what is the scientific method?