Question

Which substance can be decomposed by physical means?
ammonia (NH3)
oxygen (O)
phosphorus (P)
silicon (Si)


Which substance cannot be broken down by a chemical reaction?
ammonia (NH3)
argon (Ar)
methane (CH4)
water (H2O)

Answer 1

Explanation:

1.= The pure substance can be either an element or a compound. Elements are those pure substances that cannot be decomposed by ordinary chemical means such as heating, electrolysis, or reaction. Gold, silver and oxygen are examples of elements

2.= chemicals elements

An element is a chemical substance make up of a particular kind of atmos and hence cannot be broken down or transformed by a chemical reaction into different element though it can be transmuted into another element through a nuclear reaction.

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