A sugar cube is supposed to be equivalent to a teaspoon of sugar. A teaspoon of sugar is about 4.2 g. Table sugar is composed of sucrose, which is a disaccharide of glucose and fructose, with a molar mass of 342.3 g/mol. This means a sugar cube contains (4.2 / 342.3 =) 0.0123 mol of sucrose, or (0.0123 x 6.022 x 10^23 =) 7.39 x 10^21 molecules of sucrose. As one molecule of sucrose contains one molecule of glucose and one molecule of fructose, then there about 7,400 million, million, million molecules of glucose in a sugar cube.
Atoms of the same element that differ in their numbers of neutrons are called isotopes. Many isotopes occur naturally. ... Different isotopes of an element generally have the same physical and chemical properties because they have the same numbers of protons and elec