What is an example of a physical change involving iron?
what is an example of a chemical change involving iron?

Explanation:

A physical change is defined as the change in which there occurs no difference in chemical composition of a substance.

For example, change in shape, size, mass, density, volume etc are all physical changes.

When we cut iron into pieces then it is a physical change because we are changing its size and not its chemical composition.

On the other hand, a chemical change is defined as the change in which there occurs difference in chemical composition of the substance.

For example, toxicity, reactivity, combustion etc are all chemical changes.

When iron rusts then an oxide layer of orange-brown color deposits on its surface due to chemical combination of air and moisture with iron. This is a chemical change.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

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