Acids & Bases — Set 1
Chemistry · अम्ल और क्षार · Questions 1–10 of 60
What is the pH value of a neutral aqueous solution at 25°C?
Correct Answer: A. 7
A pH of 7 represents a neutral solution where hydrogen and hydroxyl ions are equal. Pure water is the most common example of such a neutral substance. The pH scale generally ranges from 0 to 14 to measure acidity or alkalinity.
Which acid is predominantly found in lemons and oranges?
Correct Answer: A. Citric acid
Citric acid is the primary organic acid found in citrus fruits like lemons. It gives these fruits their characteristic sour taste and acts as a natural preservative. This acid is also widely used as a flavoring agent in the food industry.
What color does blue litmus paper turn when dipped in an acidic solution?
Correct Answer: B. Red
Acids turn blue litmus paper red due to the chemical reaction with hydrogen ions. This is a standard qualitative test used to identify acidic substances in laboratories. Litmus is a natural dye extracted from lichens.
Which of the following is commonly known as 'Milk of Magnesia'?
Correct Answer: C. Magnesium hydroxide
Magnesium hydroxide is called Milk of Magnesia because of its milk-like appearance when suspended in water. It is frequently used as an antacid to neutralize excess stomach acid. It is considered a weak base and is safe for medicinal use.
Which gas is evolved when a dilute acid reacts with a metal like zinc?
Correct Answer: D. Hydrogen
Hydrogen gas is produced when metals react with acids through a displacement reaction. This gas can be identified by the 'pop' sound it makes when a burning splinter is brought near. Most reactive metals follow this general chemical behavior with dilute acids.
What is the chemical name of Vinegar?
Correct Answer: D. Acetic acid
Acetic acid is the main component of vinegar, usually present in a 5-8% concentration. Its systematic IUPAC name is ethanoic acid and it has a pungent smell. Vinegar is commonly used in cooking and food preservation globally.
Which of the following bases is highly soluble in water and termed an 'Alkali'?
Correct Answer: C. Sodium hydroxide
Sodium hydroxide is an alkali because it dissolves completely in water to release hydroxide ions. Not all bases are soluble in water, but those that are are specifically called alkalis. It is a strong base often used in the manufacture of soaps.
Which acid is present in the sting of an ant?
Correct Answer: A. Formic acid
Formic acid, also known as methanoic acid, is injected into the skin during an ant bite. It causes the sharp burning sensation and irritation associated with the sting. Applying a weak base like baking soda can help neutralize this acid.
What is the pH of a solution that turns phenolphthalein indicator pink?
Correct Answer: B. More than 7
The correct answer is 'More than 7'. Phenolphthalein turns pink in basic solutions where the pH is typically above 8.2. In acidic or neutral solutions, this synthetic indicator remains completely colorless. It is widely used in acid-base titrations to find the equivalence point.
Which of the following is a strong mineral acid?
Correct Answer: D. Sulfuric acid
Sulfuric acid is a strong mineral acid that ionizes completely in aqueous solutions. It is often referred to as the 'King of Chemicals' due to its vast industrial applications. Mineral acids are derived from inorganic minerals rather than organic matter.