Answer:

Explanation:
Assuming that all caculations are at normal pressure and -1.72°C :

Where
is the number of moles of hydrogen
is the mass of hydrogen
is the density of hydrogen
Any given experiment has numerous control variables, and it's important for a scientist to try to hold all variables constant except for the independent variable. If a control variable changes during an experiment, it may invalidate the correlation between the dependent and independent variables.
It’s copied and pasted from google so make sure to put it in your words :)
No. Oxygen isn't even a metal.
Alkaline earth metals are the elements of the second column of the periodic table.
The correct answer is C) A substance changes color when heated, but changes back when cooled. Hope this helps.
Answer:
A working model used to test a design is called a
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