Which of the following is a base?

KOH which is Potassium hydroxide  is a base.

In Chemistry, A base is defined as a chemical substance which when dissolved in water gives a slippery feel,  it has a bitter taste and turns red litmus paper blue.

Another definition  is that a base is referred to as a species that  gives out  hydroxide (OH-) ions in aqueous solution, it also freely donates electrons, and takes  protons,

We have Strong bases and weak bases.

Examples of some bases areetc Sodium hydroxide, NaOH, Potassium hydroxidem,KOH  and Cesium hydroxide, CsOH

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b. KOH (potassium hydroxide)

1.solid

2.carbon dioxide

3.helium