Answer: Carbon dioxide is a pure substance.
Explanation: A pure substance is defined when a substance has a single type of molecule. If more than 1 type of molecule is present in a substance, then it is considered as a mixture.
- Soda is basically a mixture of water and carbon dioxide. More than 1 type of molecule is present.
- Gasoline is a mixture of may gases. More than 1 type of molecule is present.
- Salt water contains salt and water molecules, hence it is considered as a mixture.
- Carbon dioxide has only 1 type of molecule which is
molecules. Hence, it is a pure substance.
Answer:
Decomposition or cracking
Explanation:
In a decomposition or cracking reaction, a single compound produces two or more simpler substances.
It involves the formation of two or more products from a single reactant.
A → B + C
A is the single reactant
B and C are the products
The driving force for such a reaction is the is high positive heat of formation of the compound that is, extreme instability of the compound.
Answer:
KNO2, KBr
Explanation:
Chemical compounds are any substance composed of identical molecules consisting of atoms of two or more chemical elements. So NO2 and KBr are compounds, Br2 and Fe are not.