Determinar el grupo atomico de un elemento "E" perteneciente al cuarto periodo y al grupo 4 A de la tabla periodica a)30
b)32
c)4
d)44
e)34

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water