Which alkali is used in barium sulfate ?

The barium

Explanation:

Barium is an alkaline earth metal that has toxic properties. It is the alkaline used in the composition of barium sulfate which is used as a contrast in stomach and intestine radiographs. This procedure presents no danger, as this sulfide is insoluble, that is, it will not be absorbed by the stomach.

Barium is a toxic chemical element, silvery in appearance, with a high melting point, which can be found in the mineral barite, not being found free in nature, due to its high reactivity.

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.

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.