Answer: hydroxide ions
Explanation:
According to the Arrhenius concept, an acid is a substance that ionizes in the water to give hydronium ion or hydrogen ion and a bases is a substance that ionizes in the water to give hydroxide ion .
According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
As KOH can give hydroxide ions on dissociation , it is considered as arrhenius base.

Answer: polar solvent
Explanation:
Polarity can be said to mean, charge separation. Thus, polar solvents are solvents that have charge separation and the ability to solvate i.e dissolve ions.
A polar solvent molecule has slight electrical charge as a result of its shape. A typical and most common example is water, with an oxygen and two hydrogen atoms. The two hydrogen atoms are at an angle to the single oxygen atom. Water is the classic polar solvent. The oxygen atom tends to polarize electron density to itself.
Answer:
b. potassium.
Explanation:
Potassium-sparing diuretics and salt substitutes are diuretics that eliminate salt and water but save potassium. They act by inhibiting the conducting sodium channels in the collecting tubule, such as amiloride and triamterene, or by blocking aldosterone, such as spironolactone.
Concomitant use of potassium-sparing diuretics together with salt substitutes may result in dangerously high blood levels of serum potassium. For this reason, it is important to consult a physician before taking these substances at the same time to avoid potential problems with potassium accumulation.