Educational worksheet on acids, bases, and salts with fill-in-the-blank and multiple-choice questions.

Problem Analysis:

The task involves understanding the concepts of acids, bases, and salts, along with their properties and uses. Let's solve each part step by step.

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Part 1: Fill in the blanks

#### a. In the presence of acid, the indicator changes into ______.
- Explanation: Indicators are substances that change color depending on the pH of a solution. Common indicators like litmus paper or phenolphthalein change color when exposed to acids or bases.
- Answer: Red (Litmus paper turns red in acidic solutions.)

#### b. ______ acid is found in orange.
- Explanation: Citric acid is a common acid found in citrus fruits like oranges.
- Answer: Citric

#### c. Water-soluble bases are called ______.
- Explanation: Bases that dissolve in water are known as alkalis. Alkalis are a subset of bases.
- Answer: Alkalis

#### d. Methyl orange changes its color from orange to red in ______ medium.
- Explanation: Methyl orange is an acid-base indicator. It changes color based on the pH of the solution. Specifically, it turns red in acidic conditions (pH < 3.1).
- Answer: Acidic

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Part 2: Who am I?

#### a. I am used in the production of disinfectants, as well as liquid soaps, shampoos.
- Explanation: Sodium hydroxide (NaOH), also known as caustic soda, is commonly used in the production of disinfectants, soaps, and shampoos due to its strong alkaline properties.
- Answer: Sodium hydroxide (NaOH)

#### b. I am a substance which when added to a solution indicates whether the substance is acidic or basic.
- Explanation: Indicators are substances that change color based on the pH of a solution, helping to determine whether it is acidic or basic.
- Answer: Indicator (e.g., litmus paper, phenolphthalein, methyl orange)

#### c. I am a salt used by your mother when she makes cakes for you.
- Explanation: Baking soda (sodium bicarbonate, NaHCO₃) is a salt commonly used as a leavening agent in baking, including making cakes.
- Answer: Baking soda (sodium bicarbonate, NaHCO₃)

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Part 3: Answer this question

#### Read the given statements given below:
- All alkalis are bases.
- Not all bases are alkalis.
- Not all bases dissolve in water.

#### Question: Which statement is correct?
- Explanation:
1. All alkalis are bases: This is true. Alkalis are a subset of bases. By definition, alkalis are water-soluble bases.
2. Not all bases are alkalis: This is also true. While all alkalis are bases, not all bases dissolve in water, so they are not alkalis. For example, ammonia (NH₃) is a base but not an alkali because it does not dissolve in water as a hydroxide.
3. Not all bases dissolve in water: This is true. Some bases, like ammonia (NH₃), do not dissolve in water as hydroxides, so they are not alkalis.

Since all three statements are correct, the answer is:

- Answer: All three statements are correct.

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Final Answers:

1. Fill in the blanks:
- a. Red
- b. Citric
- c. Alkalis
- d. Acidic

2. Who am I?
- a. Sodium hydroxide (NaOH)
- b. Indicator
- c. Baking soda (sodium bicarbonate, NaHCO₃)

3. Which statement is correct?
- All three statements are correct.

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Boxed Final Answer:

\[
\boxed{
\text{1. a. Red, b. Citric, c. Alkalis, d. Acidic} \\
\text{2. a. Sodium hydroxide (NaOH), b. Indicator, c. Baking soda (NaHCO₃)} \\
\text{3. All three statements are correct.}
}
\]