Exam-style CBSE practice questions on How Strong are Acid or Base Solutions? (Acids, Bases and Salts). Try each one first, then reveal the correct answer and a step-by-step explanation. Free, from EduLevel — the AI teacher for CBSE.
If a solution changes the color of red litmus to blue, what is its likely pH value?
Think about the properties of acids and bases. Which type of substance turns red litmus paper blue?
Explanation: A solution that turns red litmus blue is basic. Basic solutions have a pH greater than 7. Among the given options, only 10 is greater than 7.
Which of the following categories of medicine is employed to alleviate indigestion?
Think about the common discomfort caused by indigestion and what type of medicine specifically targets stomach acidity.
Explanation: Indigestion is caused by excess stomach acid. Antacids are basic substances that neutralize this excess acid, providing relief.
It is observed that 10 mL of a sodium hydroxide (NaOH) solution is completely neutralized by 8 mL of a specific hydrochloric acid (HCl) solution. If we use 20 mL of the same NaOH solution, what volume of the same HCl solution will be needed for complete neutralization?
This problem involves a chemical reaction where a base (NaOH) reacts with an acid (HCl) in a process called neutralization. Think about how the amounts of reactants are related in such reactions.
Explanation: The ratio of volumes for neutralization is constant. Since the volume of NaOH is doubled (from 10 mL to 20 mL), the volume of HCl required will also double (from 8 mL to 16 mL).
What is the specific pH range within which the human body's metabolic processes function correctly?
Think about whether the human body tends to be slightly acidic, neutral, or slightly alkaline for optimal function. Most biological systems operate very close to a neutral pH.
Explanation: The human body maintains a narrow pH range of 7.0 to 7.8 for its biological and metabolic activities to function optimally.
Tooth enamel, which is composed of calcium hydroxyapatite (a form of calcium phosphate), begins to corrode when the pH in the mouth drops to which of the following values?
Consider the concept of acidity and how it affects different substances. What is the typical pH range for neutral, acidic, and alkaline solutions?
Explanation: Tooth decay initiates when the pH level in the mouth falls below 5.5, as the acidic environment starts to demineralize the tooth enamel.
Given three aqueous solutions: A (Potassium nitrate), B (Ammonium chloride), and C (Sodium carbonate), select the option that shows the correct increasing order of their pH values.
Consider the nature of the salts formed from strong/weak acids and strong/weak bases. How does this relate to pH?
Explanation: Ammonium chloride (B) is a salt of a weak base and strong acid, so it's acidic (pH < 7). Potassium nitrate (A) is a salt of a strong acid and strong base, so it's neutral (pH ≈ 7). Sodium carbonate (C) is a salt of a strong base and weak acid, so it's basic (pH > 7). Therefore, the increasing order of pH is B < A < C.
Tamarind juice turns blue litmus paper red. This indicates the presence of which acid?
Acids have the property of turning blue litmus paper red. This question is about identifying the specific acid found in tamarind that exhibits this acidic property.
Explanation: Tamarind is a natural source of tartaric acid, which is responsible for its acidic properties and its effect on litmus paper.
Fresh milk has a pH of 6. To prevent it from curdling quickly, a specific chemical substance is added. Identify this substance.
Think about the chemical property of milk that leads to curdling and what kind of substance would counteract that.
Explanation: Milk curdles due to the formation of lactic acid, which lowers its pH. Adding a mild base like sodium hydrogen carbonate neutralizes the acid, thus delaying the curdling process.
When a few drops of universal indicator are added to a solution, it turns a yellowish-orange color. What is this solution likely to be?
The color of the universal indicator tells us about the pH of the solution. What does a yellowish-orange color generally indicate about the acidity or alkalinity of a substance?
Explanation: A yellowish-orange color with a universal indicator corresponds to a weakly acidic solution (pH around 3-5). Among the choices, lemon juice is acidic.
Anita tested diluted acetic acid and diluted hydrochloric acid with pH paper and compared the resulting colors. Which of the following conclusions is correct?
Consider the relative strengths of acids. How does the degree of dissociation affect the concentration of H+ ions in a solution?
Explanation: Hydrochloric acid is a strong acid that dissociates completely, resulting in a lower pH. Acetic acid is a weak acid that dissociates partially, leading to a comparatively higher pH for the same concentration.
An aqueous solution 'A' changes the color of phenolphthalein solution to pink. When another aqueous solution 'B' is added to 'A', the pink color vanishes. Which of the following statements correctly describes solutions 'A' and 'B'?
Think about what causes phenolphthalein to turn pink. This color change is an indicator of a specific type of chemical environment.
Explanation: Solution 'A' turns phenolphthalein pink, indicating it is a base (pH > 7). Solution 'B' neutralizes it, causing the color to disappear, which means 'B' must be an acid (pH < 7).
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