You have 75.0 ml of a 2.50 m solution of na2cro4(aq). you also have 125 ml of a 1.79 m solution of agno3(aq). calculate the concentration of cro42– after the two solutions are mixed together.

The reaction of Na2CrO4 (aq) and AgNO3 (aq) is as follows:
2AgNO3 (aq) +Na2CrO4 (aq) ⇒Ag2CrO4 (s) + 2NaNO3 (aq).

During this reaction, part of the CrO42- reacts with Ag+ and precipitates out of the solution, part of the CrO42- (excess amount) remains in the solution. 

To find out how much CrO42- is reacted:
Moles of initial CrO42- = 0.075 L * 2.5 M = 0.1875 mole
Moles of initial Ag+ = 0.125 L * 1.79 M = 0.2238 mole

The reaction ratio between CrO42- and Ag+ is 1:2 according to the equation.  So moles of CrO42- that is reacted is 0.2238 mole/2 = 0.1119 mole.  Therefore, moles of CrO42- that remains in the solution is 0.1875mole-0.1119mole = 0.0756 mole

So the final concentration of CrO42- in the solution is 0.0756mole/(0.075L+0.125L)= 0.378 M.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

C) the increase in atmospheric pressure pushes the walls of the balloon outward thus making it  is the answer.hope i you.