A student is asked to prepare 400.0 mL of a 0.25M HCl solution. The students find a bottle labeled ""2.0M HCl."" How many mL of the 2.0M solution are needed to prepare the 0.25M solution?

The answer to your question is He needs 50 ml of 2.0 M HCl.

Explanation:

Data

Volume 2 = 400 ml

[HCl] 2 = 0.25 M

[HCl] 1 = 2.0 M

Volume 1 = ?

To solve this problem use the dilution formula

Formula

                     V₁C₁  =  V₂C₂

Solve for V₁

                     V₁ = V₂C₂ / C₁

Substitution

                      V₁ = (400)(0.25) / 2

Simplification

                      V₁ = 100 / 2

Result

                      V₁ = 50 ml

trigonal pyramidal

tetrahedral

trigonal planar

bent

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.