.. A … are physical devices that are used for a better visualisation and perception of three dimensional shapes of organic molecules. Here, A refers to

Options

A. Molecular models
B. Biomolecular models
C. Chemical models
D. Science models

Answer

To solve the question, we need to identify what "A" refers to in the context of physical devices used for visualizing the three-dimensional shapes of organic molecules.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a term that describes physical devices that help visualize and perceive the three-dimensional shapes of organic molecules.

2. **Identifying the Context**: The context is organic chemistry, where understanding the spatial arrangement of atoms in molecules is crucial for grasping their properties and reactivity.

3. **Considering Common Tools**: In organic chemistry, various tools are used to represent molecular structures. These can include drawings, models, and software. However, the question specifically mentions "physical devices."

4. **Recognizing Molecular Models**: One of the most common physical devices used for this purpose is molecular models. These models consist of balls representing atoms and sticks representing bonds, allowing for a tangible representation of molecular geometry.

5. **Conclusion**: Based on the understanding that molecular models provide a three-dimensional visualization of organic molecules, we can conclude that "A" refers to "Molecular Models."

### Final Answer:
A = Molecular Models

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