In this numbered error spotting question, read the sentence and identify the part that contains an error. The sentence is: "The teacher instructed the students (1) to have a thoroughly reading (2) of each chapter (3) mentioned in the syllabus. (4)" Choose 1, 2, 3, or 4. If there is no error, the answer would be 4.

Introduction / Context:
This question checks your understanding of correct word forms in noun phrases. The teacher wants students to read each chapter carefully. The sentence has been divided into four numbered parts, and you must identify which part contains an error. The key phrase here is "to have a thoroughly reading", which may sound wrong if you know how adverbs and adjectives work in English.

Given Data / Assumptions:

• Sentence parts:
  • (1) The teacher instructed the students
  • (2) to have a thoroughly reading
  • (3) of each chapter
  • (4) mentioned in the syllabus.
• Options: 1, 2, 3, 4.
• The intended meaning is that students should read each chapter in a thorough manner.

Concept / Approach:
In English, "thorough" is an adjective, and "thoroughly" is an adverb. When we want to describe a noun like "reading", we should use the adjective "thorough", not the adverb "thoroughly". The phrase should be "a thorough reading", not "a thoroughly reading". Alternatively, we can use "read each chapter thoroughly", where "thoroughly" modifies the verb "read". In the given sentence structure, the correct choice is an adjective before the noun "reading".

Step-by-Step Solution:
Step 1: Examine part (1): "The teacher instructed the students" is grammatically correct and sets the context. Step 2: Examine part (2): "to have a thoroughly reading". Here, "thoroughly" is an adverb, but it is placed before the noun "reading". Step 3: Recognise that an adjective should modify the noun "reading". Therefore, the correct phrase is "a thorough reading". Step 4: Part (3): "of each chapter" correctly indicates what is to be read. Step 5: Part (4): "mentioned in the syllabus" correctly forms a past participle phrase modifying "chapter". Step 6: Conclude that the error lies in part (2), which should be changed to "to have a thorough reading".

Verification / Alternative check:
Rewrite the full corrected sentence: "The teacher instructed the students to have a thorough reading of each chapter mentioned in the syllabus." This version is standard exam English. If we leave "thoroughly" as it is, the phrase becomes ungrammatical. Changing any other part would spoil correct structures like "instructed the students" or "of each chapter mentioned in the syllabus". This confirms that only part (2) is problematic.

Why Other Options Are Wrong:
Part (1) correctly uses past tense "instructed" with the object "the students".

Part (3) correctly uses the preposition "of" to join "reading" and "each chapter".

Part (4) correctly uses "mentioned in the syllabus" as a reduced relative clause describing "chapter".

Common Pitfalls:
Students sometimes confuse where to use adverbs and where to use adjectives, especially with words that have both forms. A helpful rule is: if you are directly modifying a noun, use an adjective ("a thorough reading"); if you are modifying a verb, use an adverb ("read thoroughly"). Keeping this in mind will help in many similar error spotting questions.

Final Answer:
The error is in part (2), so the correct option is 2.