Selma made an error while creating a chart to describe the technological design process for a new vacuum. Which best describes how Selma can correct the error in her chart? Change “Identify a need” to “Identify a problem.” Switch the descriptions for “Identify a need” and “Evaluate the solution.” Change “Implement the solution” to “Test the prototype.” Switch the stages “Evaluate the solution” and “Design a solution.”

d

Explanation:

switch the stages evaluate the solution and design a solution

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.