Upal. Consider the elements sodium, aluminium, silicon and sulphur. Which one will form
an oxide that will give a pH of less than 7 when in solution?​

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sodium

Explanation:

this is because sodium is neutral hence the pH formed will be 7

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as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.