Answer:
i think its 2
Explanation:
because the H2 is seperate from the others it is the only one with a number.
<em>Answer:</em>
<em>Chemical properties:</em>
Those properties which change the chemical nature of matter.
<em>Example:</em>
- Heat of combustion
- Enthalpy of formation
<em>Physical properties:</em>
Those properties which do not change the chemical nature of matter.
<em>Example</em>
<em>Differences between chemical and physical properties:</em>
Chemical properties Physical properties
1. Observed after the change bringing 1. Observed with out being
the change change
2. These changes the molecules 2. only change physical state
3. Chemical identity changes 3.Chemical identity not changes
4. Structure of material changes 4.Structure of material not change
5. Chemical reaction is needed 5. No need of Chemical reaction
6. depend on composition 6. Does not depend on composition
Example #1 write the chemical formula for Calcium Oxide
Step 1
-Find the Atomic symbol of the metal and non-metal on the periodic table
CaO
Step 2
Find the charges for Calcium and Oxygen
which are Ca 2+ and O 2-
Step 3
Balance out the charges
They are already balanced out
Here´s the chemical formula for Calcium Oxide
CaO
Example 2 write the chemical formula for Aluminum Oxide
Step 1
-Find the Atomic symbol of the metal and non-metal on the periodic table
A
l
O
Step 2
Find the charges for Aluminum and Oxygen
Which are Al 3+ and O 2-
Step 3
Balance out the charges
You need 2 Aluminum and 3 Oxygen to balance the charges
Al 3+ O 2-
Al 3+ O 2-
= 6 + O 2-
= 6-
Step 4
If you need more then one element to balance out the charges you identify that by using subscripts
Heres your chemical formula for Aluminum Oxide

The rate of the reaction is measurable quantity that refers to the amount or how much is are chemical substances reagents used up or converted into the product over some period of time.
Rate = change in the amount/time.
This can indirectly be observed through many ways, such as the volume of gas given off if the byproduct is a gas being produced, the colour of the solution etc.