When were earth’s landmasses first recognizable as the continents we know today

What is meant by the statement" the melting poin of glycerine is 13 degree celsius

How many hydrogen (h) atoms are in one molecule of sulfuric acid, h2so4? (1 points) 1 2 4 7

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.