Define Acid and alkalis​

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Explanation:

An acid is a substance that has a pH lower than 7. For example, hydrochloric acid, sulphuric acid, citric acid, ethanoic acid (vinegar). A base is a substance that neutralises an acid – those that dissolve in water are called alkalis. An alkali is a soluble substance with a pH higher than 7.

The chemical which give hydrogen ion when dissolve in water is called acid.for example:HCL,HNO3,H2SO4 etc.

The bases that dissolve in water and produce hydroxyl ions are called alkalis.for example:NaOH,KOH etc.

Explanation:

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.