Which substance can not be broken down by a chemical change? a)methane b)propanal c) tungsten d)water

Explanation:

Chemical compounds are pure substances constituted by two or more different elements. They have fixed composition and have their unique chemical properties, different from their individual components (elements) and from other compounds.

Thus chemical compounds can be broken down by a chemical change into their individual atoms or other simpler compounds.

The substances indicated by the choices A) methane, B) propanal, and D) water, are chemical compounds with chemical formulae CH₄, C₃H₆O, and H₂O, respectively, so they can be broken down into their consitutents by a chemical change.

On the other hand, tungsten is one of the 118 known elements. Its atomic number is 74, and its chemical symbol is W.

Then, being tungsten an element, which means that all the atoms present in a pure sample have the same number of protons and electrons, it cannot be broken down by a chemical change. The only way to split an atom of tungsten is by a nuclear reaction.

Explanation:

Tungsten cannot be broken by any physical or chemical methods, because it is an element. It has properties of an element not a compound nor mixture.

Tungsten is an element in the periodic table with an atomic number of 74, symbol W, and atomic mass of 183.84 u.

Tungsten is also a rare metal and is the strongest known metal on Earth. Tungsten can be used to make bullets and missiles.