Somebody i have no idea what the correct answer is! (iii) and (iv)

The following reaction shows sodium carbonate reacting with calcium hydroxide. na2co3 + ca(oh)2 → naoh + caco3 how many grams of naoh are produced from 20.0 grams of na2co3? (molar mass of na = 22.989 g/mol, c = 12.01 g/mol, o = 15.999 g/mol, ca = 40.078 g/mol, h = 1.008 g/mol) 12.2 grams 15.1 grams 24.4 grams 30.2 grams

What human activity increases beach erosion?

Which of the following reasons best explains why a scientist would want to replicate gregor mendel's pea plant experiment? a. to discover new aspects of the natural world b. to test the predictions of current theories c. to explain recently observed phenomena d. to test the conclusions of prior investigations