Railway Science (Chemistry-Acid ,Bases and Salt) (Part-III)

Total Questions: 50

31. Which of the following statements is true/false? [RRB Group D 15/11/2018 (Evening)]

A. An acid that completely ionizes into ions produces a greater number of H⁺  ions. For example HCI, H₂SO₄, HNO₃
B. An acid that partially ionizes in water produces small numbers of H⁻ ions. For example CH₂COOH, H₂CO₃, H₂SO₃

Correct Answer: (a) Only A is true.
Solution:

Acetic acid (CH₃COOH), carbonic acid (H₂CO₃), and sulfurous acid (H₂SO₃) are weak acids, meaning they don't fully ionize but still release some H⁺ ions in water. Acids are defined as being able to donate protons in the form of hydrogen ions; whereas bases are defined as being able to accept protons.

32. Due to an increase in ______ acid, muscle cramps occur. [RRB Group D 16/11/2018 (Morning)]

Correct Answer: (b) lactic
Solution:

When muscle cells respire anaerobically, they produce lactic acid, which accumulates and contributes to muscle cramps. Massaging muscles enhances blood circulation, increasing oxygen supply to cells. This helps break down lactic acid into carbon dioxide and water, providing relief from muscle cramps.

33. Which of the following statements is true/false? [RRB Group D 16/11/2018 (Afternoon)]

A. A base that completely ionizes in water produces large amounts of OH⁺ ions. For example NaOH, KOH
B. A base that partially ionizes in water produces small amounts of OH⁻ ions. For example KOH

Correct Answer: (a) Both A and B are false.
Solution:

An acid which is completely ionized into ions and produces a large number of H⁺ ions is a strong acid. Examples: HCl, HNO₃ . An acid which is partially ionized in water and produces fewer H⁺ ions is a weak acid. Examples: CH₃COOH, H₂SO₂ .

34. Which of these acids is present in spinach and tomato? [RRB Group D 26/11/2018 (Afternoon)]

Correct Answer: (d) Oxalic acid
Solution:

Natural acids and their sources: Acetic acid - Vinegar, Formic acid - Ant’s sting, Citric acid - lemons, Lactic acid - Curd, Ascorbic acid - Amla, Tartaric acid - Tamarind, grapes, unripe mangoes.

35. What happens to an acid or a base in a water solution? [RRB Group D 27/11/2018 (Morning)]

Correct Answer: (d) Bases give OH⁻ in water.
Solution:

Bases turn the color of red litmus  paper to blue. Example - NaOH (s)⟶ Na⁺ (aq) + OH⁻ (aq). An acid is a substance that forms hydrogen ions (H⁺) when dissolved in water. The color of blue litmus paper to red. Example - HCl (g)⟶ H⁺ (aq) + Cl⁻ (aq).

36. If the soil is treated with mild acid, the flowers in Hydrangea Gulma in this soil will be ____. [RRB Group D 28/11/2018 (Morning)]

Correct Answer: (b) Blue color
Solution:

Color variation in hydrangeas is due to the presence or absence of aluminum compounds in the flowers. If aluminum is present, the color is blue. If it is present in small quantities, the color is variable between pink and blue. If aluminum is absent, the flowers are pink.

37. Tooth enamel is made up of _______, which when destroyed by acid causes tooth decay. [RRB Group D 3/12/2018 (Evening)]

Correct Answer: (b) Calcium phosphate
Solution:

It does not dissolve in water but it starts corroding when the pH in the mouth decreases to 5.5 or less. Tooth enamel is the hardest substance in the human body.

38. Which one of the below is not a property of acids? [RRB Group D 4/12/2018 (Morning)]

Correct Answer: (a) Their presence turns red litmus blue
Solution:

Properties of acid - Acids turn blue litmus red and have a sour taste, It turns methyl orange to red, Strong acids destroy fabric. Acids donates Hydrogen ions (𝐻⁺) in aqueous + solutions. Properties of Base - Bases change the color of litmus from red to blue, they are Bitter in taste, It releases Hydroxide ions (𝑂𝐻⁻) when it is in − solution. When Acid reacts with Base, it produces Salt and water (Acid-Base Reaction also called neutralization).

39. What color does the litmus solution change when mixed with sulfuric acid? [RRB Group D 06/12/2018 (Afternoon)]

Correct Answer: (b) red
Solution:

Litmus: It is extracted from lichens. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it turns red and when added to a basic solution, it turns blue. It is available in the form of a solution, or in the form of strips of paper, known as litmus paper.
Acid: Acetic acid - Vinegar. Formic acid - Ant’s sting. Citric acid - Citrus fruits such as oranges, lemons, etc. Lactic acid - Curd. Oxalic acid - Spinach. Ascorbic acid - Amla, Citrus fruits (Vitamin C). Tartaric acid - Tamarind, grapes, unripe mangoes, etc.

40. What is the change in the pH of the solution if its hydrogen ion concentration increases ? [RRB Group D 10/12/2018 (Afternoon)]

Correct Answer: (d) pH will decrease.
Solution:

The pH of a solution is a measure of the concentration of hydrogen ions (H⁺ ) in the solution. pH is defined as the negative logarithm of the hydrogen ion concentration.