Describe two chemical reactions that require energy in order to occur

After the collapse of a nebular cloud, atoms begin gravitating together to form a condensed center. What happens next in the star formation process?

Which of the following is the simplest representation of a molecule and its bonds?

The symbol of an element represents one atom of that element Ba=

Draw the lewis dot structures for each of the following molecules. show the resonance structures, if they exist A. O2 B. CO C. N2 D. SO2

Define le chatelier's principle. define le chatelier's principle. when a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance. a system will always change if the pressure changes.

In the reaction, Zn + HCl-> ZnCl2 + H2, 25 grams Zn are reacted with 17.5 grams HCl. How many grams of H2 will be produced? A. 0.382 g of H2 B. 0.479 g of H2 C. 0.7865 g of H2 D. 0.484 g of H2

Is nail varnish soluble?

What is the periodic trend for atomic size from top and bottom in a group? From left to right in a period?

Which planets' orbits is the belt located between the main asteroid belt?

For the baeyer-villiger oxidation of cyclohexyl methyl ketone