Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?
A new substance is produced
This change is a --------------- ( physical change- Chemical change )
physical change
The reactants in the image above are:(CH4 and 2 O2----2 H2O and CO2)
CH4 and 2 O2
Is burning wood a chemical or physical change?
chemical
Which example provides evidence of a chemical change? 1-Wood releases ash and smoke when burned.-2-Boiling water bubbles when being heated.-3-Rock particles separate when soil is being sifted.
Wood releases ash and smoke when burned.
How many hydrogen atoms are in this chemical formula CH4 : (4-1-2-3) Hydrogen atoms
4 hydrogen atoms
What is a chemical reaction? 1-a change in matter when the molecules rearrange to make new molecules //2-a change in matter when matter changes its form or appearance
a change in matter when the molecules rearrange to make new molecules
Is glass breaking a chemical or phyiscal change?
physical
When materials combine to form new compounds it is a chemical change. Which example is a chemical change?( baking powder fizzing-water boiling-ice melting-sugar cube dissolving)
baking powder fizzing
A group of atoms bonded together. (A Molecule --- The Coefficient--- The Subscript---- An Atom Party)
A Molecule
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