No, elements are pure substances. However, if you mix two elements together, it depends on how well you mix them. Mixtures of two elements can be completely homogeneous, or extremely heterogeneous.
Brass is a homogeneous mixture. It is made up of a combination of copper and zinc, which are two elements. As a homogeneous mixture, brass has a uniform composition and properties throughout.
No, Concrete is a homogeneous mixture.
Visible particles would be heterogeneous elements of a mixture. A truly homogeneous mixture would have no visible particles. However, you could still have an approximately homogeneous mixture with visible particles, evenly distributed throughout the mixture.
A leaf is a homogeneous mixture. This means that it is uniformed and has the same elements that are found throughout.
Nickel and silicon are elements. Gasoline is a homogeneous mixture.
Calcium bromide, CaBr2, is a compound. It is not an element, because elements are individual species and they are found in the periodic table. It is not a homogeneous or heterogeneous mixture, because it is a single entity.
This mixture is not homogeneous.
A heterogeneous mixture is a sum of pure substances which are not soluble in each other while a homogeneous mixture is a mixture wherein its constituents do not appear separately. Methanol is an example of a homogeneous mixture.
Bronze is an alloy. I've never heard of classifying metals as homogeneous or heterogeneous. If I had to put it in one, well it's definitely not heterogeneous, because that would consist of a mixture of dissimilar components. An alloy has a uniform 'mixture' of elements, so I guess that would make it homogeneous!
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