Question

1. A substance that can be separated into two or more substances only by a chemical change is a(n) _____.

solution
element
mixture
compound

2.
Which of the following materials is a substance?

air
gasoline
stainless steel
silver

3.
The first figure in a properly written chemical symbol always is _____.

boldfaced
capitalized
italicized
underlined

4.
Which of the following represents a compound?

H
H-3
H2O
O-16

5. What do chemical symbols and formulas represent, respectively?

elements and compounds
atoms and mixtures
compounds and mixtures
elements and ions

Answer 1

These are five questions and five answers.


1. A substance that can be separated into two or more substances only by a chemical change is a.

Answer: compound


Explanation:


i) solution is a homogenous mixture and it can be separated by physical media. For example, a brine: you can evaporate the water from the salt by heating the solution (brine)


ii) elements cannot be separated into two or more substances except by nuclear reactions.


iii) mixtures: heterogenous and homogenous mixtures can be separated by physical treatments.


iv) compounds are substaces composed of different elements bonded chemically; only chemical reactions break the chemical bonds or create new chemical bonds leading a compound to form other substances.


2. Which of the following materials is a substance?


Answer: silver


Explanation:

Substances have a definite composition that can only be modified by chemical reactions.


Elements and compounds are substances.


Silver is an element, such as sodium, gold, oxygen. You can find the list of the 118 known elements in a periodic table.


Mixtures, either homogenous or heterogeneous, can be separated by physical mechanisms and so they are not substances: air, gasoline, and stainless steel are mixtures because they have not a unique chemical formula but are formed by other compounds or elements in different proportions, i.e. with not a unique chemical formula.

3.The first figure in a properly written chemical symbol always is _____.


Answer: capitalized


Explanation:


This is a rule to write the symbols of the elements. For example, Na (sodium), Br (bromine), I (iodine), O (oxygen), Ne (neon).

4. Which of the following represents a compound?


Answer: H2O


Explanation:


That is the only chemical formula. The other representations are not valid chemical formulas. A chemical cormula can oly contain chemical symbols and subscript numbers, to represent the kind of atoms (elements) and how many of each (the subscrip).

5. What do chemical symbols and formulas represent, respectively?


Answer: elements and compounds


Justification:


1) The symbols are used to represnt elements, such as Na (sodium), Li (lithium), Be (berylium)


2) Chemical formulas represent compunds. For example: CO is carbon monoxide, CO2 is carbon dioxide, H2CO3 is carbonic acid, Na2CO3 is sodium carbonate.


Each compound has a unique chemical formula.

Answer 2

1. A substance that can be separated into two or more substances only by a chemical change is a compound.
2. Silver is a substance.
3. The first figure in a properly written chemical symbol is always capitalized.
4. H₂O represents a compound.
5. Chemical symbols and formulas represent elements and compounds, respectively.

FURTHER EXPLANATION

Question 1

• Solution is a homogeneous mixture. Mixtures are two or more pure substances that are combined only physically. They only share the same space but are not chemically bonded to each other. Therefore, they can be separated by physical means. It is homogeneous because the mixture appears to be in one uniform state.

• Element is the type of pure substance that cannot be broken down to simpler substances.

• Mixture is a physical combination of two or more elements or compounds. They share the same space or container only but do not mix chemically. Properties of individual components are retained and they can be obtained by physical processes.

• Compound is composed of two or more elements that are chemically combined. The properties of the compound are different from the properties of the individual elements that make up the compound. Chemical processes are required to breakdown a compound into its component elements.

Question 2

A pure substance is either an element or a compound.

• Air is a mixture of gases.

• Gasoline is a mixture of different hydrocarbons.

• Stainless steel is a mixture of metals like including chromium, nickel, and iron.

• Silver is an element.

Question 3

Elements in the periodic table are assigned one or two letter symbols. The first letter is always capitalized and the second letter, if any, is always in lower case. These chemical symbols are based on the names (old or new) of the element.

Question 4

A compound is composed of two or more elements that are chemically combined.  

• H is the symbol for hydrogen which is simply am element on its own.

• H-3 is an isotope of hydrogen. It is a version of the hydrogen atom which has 2 additional neutrons in the nucleus. It is represented here through the hyphen notation for an isotope.

• H₂O is the chemical formula for water which is a compound made up of two hydrogen atoms and an oxygen atom.

• O-16 is an isotope of oxygen.

Question 5

• Elements and compounds are represented by chemical symbols and formulas, respectively.

• Atoms and mixtures may be represented diagrammatically using spheres to represent individual atoms.

• Compounds are represented by chemical formulas but mixtures are represented using the chemical formulas of its component compounds often written with the ampersand sign (&) to indicate that it is a physical combination only.

• Elements are represented by chemical symbols and ions are also represented through the symbol of the element but with a positive or negative superscript depending on their net charge.

LEARN MORE

1. Naming Compounds https://brainly.com/question/8968140
2. Chemical Formulas https://brainly.com/question/4697698

Keywords: elements, compounds, mixtures, chemical formula