The correct option is Only two
Explanation
Bases are chemical substances characterized by a bitter taste and a soapy feel. They produce hydroxide ions ($OH^-$) in aqueous solutions. Various bases are active ingredients in common household products.
- Pair 1 is correctly matched: Calcium hydroxide ($Ca(OH)_2$) is commonly known as lime water when dissolved in water. It is used in whitewashing and in the laboratory to test for carbon dioxide.
- Pair 2 is correctly matched: Ammonium hydroxide ($NH_4OH$) is a weak base found in window cleaners and glass cleaning agents. It is effective at removing grease and dirt without leaving streaks.
- Pair 3 is incorrectly matched: Magnesium hydroxide ($Mg(OH)_2$) is the main component of Milk of magnesia, which is used as an antacid to neutralize excess stomach acid. Soaps are typically made from Sodium hydroxide ($NaOH$) or Potassium hydroxide ($KOH$).
- Pair 4 is incorrectly matched: Sodium hydroxide ($NaOH$) is a strong base used in the manufacturing of soaps, detergents, and paper. Milk of magnesia contains Magnesium hydroxide.
Key Takeaway: Common bases and their sources include Calcium hydroxide (Lime water), Ammonium hydroxide (Window cleaner), Sodium/Potassium hydroxide (Soap), and Magnesium hydroxide (Milk of magnesia).