Astudent performs an experiment to find the percentage of water in a hydrate. he determines that the hydrate contains 22% water, but the teacher tells him that it actually contains 40% water. what error may have caused him to obtain this low value?

A feasible error could have been the removal of the sample before all water evaporated.

Explanation:

In order to determine the percentage of water in an hydrate, an experiment that could be performed is the heating of the sample until the mass does not change. If the student heated the sample an insufficient amount of time, water will be present in the sample, thus reducing the percentage reported.

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.

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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.  

a) the particles of the chair are strongly held together.