Which of the following materials would be less suitable for a balcony window?

A hopper window is generally less suitable for a balcony setting due to its design and operational characteristics. Hopper windows are characterized by their top-hinged design that opens inward, typically from the bottom. This opening style can interfere with the usable space on a balcony and may pose safety concerns, especially in narrower areas where a window that opens inward might obstruct movement or create a hazard.

In contrast, other window types, such as double-hung, fixed, and casement windows, have designs that can be more accommodating in a balcony scenario. A double-hung window can offer ventilation without protruding into the balcony space, while a fixed window provides unobstructed views without the potential safety issues of an opening window. A casement window also swings outward, which can be beneficial in some balcony designs, as it does not interrupt the internal layout or space.