How many moles are in 2.78 x 10^25 ion of sodium? someone help please

Often on a topographic map, every fifth contour line is darkened. what is this line called? a. key b.slope c.benchmark d. index contour

Which of the following statements about acidic water is true? a. acid has no effect on the h,o molecules. b. the solution contains a larger number of oh ions than h,o ions. c. the solution contains a larger number of h,o ions than qh ions. d. the solution contains an equal number of h,o ions and oh ions. none of the above e.

In a reaction (at equilibrium) that makes more moles of gas than it consumes, what is the effect of increasing the pressure?