In the sentence As feared, (differences into) the families pose a hurdle, which phrase should replace the bracketed words to make the sentence grammatically correct?

Introduction / Context:
Although listed under chemistry, this question actually tests English grammar and correct usage of prepositions in a common expression. Competitive exams often mix basic language questions into general knowledge sections. The sentence given uses a bracketed phrase that is grammatically wrong, and you are asked to select the phrase that correctly shows a contrast or separation between two families.

Given Data / Assumptions:

• Sentence: As feared, (differences into) the families pose a hurdle.
• The bracketed phrase needs to be replaced with a grammatically correct alternative.
• We assume the intended meaning is that existing differences between two families are creating a problem.
• Options include several phrases built around the word difference or differences.

Concept / Approach:
In English, when we talk about how two groups or people are not the same, we usually use the preposition between after the word differences. The standard collocation is differences between the families. Prepositions like into or amongst would not fit naturally in this structure. Therefore, the correct improvement will use the plural noun differences followed by between to connect the two sides that are in disagreement.

Step-by-Step Solution:
Step 1: Consider the intended meaning of the sentence. It suggests that there are disagreements or differences separating the families, and these differences are causing a hurdle. Step 2: In English, when we compare or contrast two groups, we normally say differences between the families. Step 3: Evaluate option A, differences into. The preposition into does not follow differences in this context and sounds incorrect. Step 4: Evaluate option B, difference as in. This phrase changes the plural to singular and uses an unnatural preposition for this sentence structure. Step 5: Evaluate option C, differences amongst. We usually use amongst when referring to differences within a single large group, not when contrasting two sides such as two families. Step 6: Option D, no improvement, would keep the clearly incorrect phrase differences into, so it cannot be right. Step 7: Option E, differences between, correctly uses the plural noun and the standard preposition for contrast between two parties. Step 8: Therefore, the bracketed part should be replaced by differences between.

Verification / Alternative check:
You can test the alternatives by reading the sentence aloud: As feared, differences between the families pose a hurdle sounds natural and clear. In contrast, As feared, differences into the families or differences amongst the families sound awkward and do not match standard English collocations. Grammar reference books and exam preparation material repeatedly use between for contrasts involving two distinct people or groups, reinforcing that between is appropriate here.

Why Other Options Are Wrong:
Differences into uses an incorrect preposition and is ungrammatical. Difference as in changes the meaning and does not correctly connect two opposing sides. Differences amongst might be used if the sentence spoke about differences amongst the family members of a single family, which is not the case here. No improvement is incorrect because the original bracketed phrase clearly contains an error.

Common Pitfalls:
A common mistake is to focus only on the noun difference or differences and ignore the preposition that follows, even though the preposition often determines correctness. Another pitfall is to overuse amongst in situations where between is required, especially when talking about exactly two clearly defined groups. Remember the simple guideline that between is usually preferred when talking about two distinct parties.

Final Answer:
The correct replacement is differences between, so the improved sentence reads: As feared, differences between the families pose a hurdle.