Why do electrons enter the 4s orbital before entering the 3d orbital?

Plant cells undergo a process called photosynthesis, which uses sunlight to make sugar. Which need does photosynthesis fulfill for plants?

Thunderclouds and rainstorms come from which type of front a. warm front b. occluded front c. stationary front d. cold front

A soccer player practices kicking the ball into the goal from halfway down the field the time it takes for the ball to get to the goal from the time it was kicked averages about 3 seconds the soccer field is 90 meters long the player wants to know

The atomic mass of europium is 151.9 amu. There are two naturally occuring isotopes on europium, eu-151 with a mass of 151.0 amu and eu153 with a mass of 153.0. The percent natural abundance of the eu151 should be

If a substance goes from the gas phase to the liquid phase, was it heated or cooled

How much heat is released if 7.15 g cao (s) is added to 152 g of h2o (l) ? cao (s) + h2o (l) → ca (oh) 2 (s) δh°rxn = - 64.8 kj/mol?

Hydrogen sulfide gas and sulfur dioxide gas react to form solid sulfur and water. If 10.0g of gaseous hydrogen sulphide is mixed with 10.0g of gaseous sulfur dioxide, how many grams of solid sulfur can form?

Describe the contributions of the following scientists to our knowledge of atomic structure: J. J. Thomson, R. A. Millikan, Ernest Rutherford, and James Chadwick

If you have 400 grams of a substance that decays with a half-life of 14 days, then how much will you have after 56 days?

As an electron gains energy, it becomes excited and jumps to a lower energy level?