una población recibe su suministro de agua directamente de u. tanque de almacenamiento si la superficie del agua contenida en el tanque se ubica a una altura de 26.0 m sobre la llave de una casa ¿ cual seria la presión del agua la llave ( desprecie los efectos de otros usuarios .) r = 255kpa​

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.