The question asks why certain food items like curd, lemon juice, and orange juice taste sour. This is a common characteristic linked to the chemical composition of these substances.
Correct Option: C) Acids are chemical compounds that typically have a sour taste. The examples provided (curd, lemon juice, orange juice) all contain various types of acids (lactic acid, citric acid) which are responsible for their characteristic sour flavor.
The question asks about the nature of baking soda. To answer this, we need to recall the chemical name and properties of baking soda, specifically its pH level when dissolved in water.
Correct Option: A) Basic
Baking soda (sodium bicarbonate) is a weak base. When dissolved in water, it produces hydroxide ions, making the solution alkaline (basic). This property is why it's used as an antacid to neutralize stomach acid and in baking as a leavening agent (reacting with acids to produce carbon dioxide).
The question asks about the applications of hydrogels. We need to evaluate each given statement to determine if hydrogels are used in those applications.
D) 1, 2 and 3 — All three statements correctly describe applications of hydrogels. Hydrogels are versatile materials used in controlled drug delivery, emerging air-conditioning technologies, and as components in industrial lubricants.
The question asks to identify the type of substances used to determine if another substance is acidic or basic. This relates to the fundamental concept of acid-base chemistry, specifically how we classify solutions based on their pH.
Correct Option: B) Indicators are substances that show different colors in acidic and basic mediums, thus helping to identify them.
The question asks to identify naturally occurring indicators from the given options. An indicator is a substance that changes color in the presence of an acid or a base. Naturally occurring indicators are those derived from natural sources like plants.
Correct Option: D) All the above. Turmeric, China rose petals, and litmus are all examples of naturally occurring indicators used to detect the acidic or basic nature of substances.
| List I | List II |
| a) Acetic acid | i.) Lemon |
| b) Formic acid | ii.) Curd |
| c) Citric acid | iii.) Ant's sting |
| d) Lactic acid | iv.) Vinegar |
The question asks to match common acids with the substances they are found in. This requires knowledge of the natural occurrence of various organic acids.
Combining these matches, we get: a-iv, b-iii, c-i, d-ii.
Correct Option: C) a-iv,b-iii,c-i,d-ii