5. A student spots an unknown sample on a TLC plate and develops it in ethanol. Only one spot appears, with an Rf of 0.97. Does this indicate that the unknown is a pure compound? What can be done to verify the purity of the sample?

At 450 mm hg a gas has a volume of 760 l, what is its volume at standard pressure

Why is the bond angle in a water molecule less than the bond angle of methane? a. the central oxygen atom in water has two lone pairs of electrons, whereas the central carbon atom in methane has no lone pairs. b. the central hydrogen atom in water has one lone pair of electrons, whereas the central carbon atom in methane has two lone pairs. c. the central oxygen atom in water has four lone pairs of electrons, whereas the central carbon atom in methane has only one lone pair. d. the central oxygen atom exerts more repulsive force on surrounding atoms than the central carbon atom in methane does. reset next

Analyze how limestone is weathered and identify the features that are formed as a result of this dissolution