Final answer:
None of the elements listed (Al, Au, Br, Ca) are typically used to fill balloons. Helium (He) is the commonly used element for this purpose, as it is a light and inert gas, but it is not listed in the options provided.
Step-by-step explanation:
In determining which of the following elements is used in balloons (Al, Au, Br, Ca), we should consider the properties necessary for a balloon gas. The most suitable elements for this purpose are inert gases because they are non-reactive and lighter than air, making them the best candidates for balloon inflation.
In the list provided, although none of the elements are inert gases, we can deduce that helium (He), an inert gas not listed, is commonly used in balloons because it is lighter than air and poses no flammability risk, unlike hydrogen (H), which is also light but highly flammable. Therefore, given the absence of helium in the options, none of the provided elements are typically used to fill balloons.
Calcium (Ca) is an alkaline earth metal, gold (Au) is a precious metal, bromine (Br) is a liquid halogen, and aluminum (Al) is a lightweight metal used in a variety of applications, but none of them is suitable for inflating balloons. Consequently, the assumption is that the question might be incorrect as intended to ask which element is used in balloons, since none of the options would match in its usual context.