It is b I hope this helps
A catalyst is a substance added to the reaction that lowers the activation energy by providing an alternate pathway for the reactions to go to completion.
A catalyst is a substance that accelerates a chemical response, or lowers the temperature or strain needed to begin one, with out itself being ate up at some stage in the response. Catalysis is the procedure of adding a catalyst to facilitate a response.
Catalysts may be categorized as homogeneous, heterogeneous, or enzymatic. Homogeneous catalysts exist inside the identical phase as the reactants, whereas heterogeneous catalysts exist in a exclusive section than the reactants.
Catalysts are basically categorised into 4 kinds.Homogeneous, Heterogeneous, Heterogenized homogeneous catalyst and Biocatalysts. Homogeneous catalyst: In homogeneous catalysis, reaction mixture and catalyst both are gift inside the equal segment.
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Answer: The green copper (II) carbonate
changes to black copper oxide 

Explanation:
Decomposition is defined as the chemical reaction in which a single compound gives two or more simple substances. It requires energy to break the bonds between reactants, thus is an endothermic process.
Thermal decomposition uses heat for decomposition.
The chemical equation for thermal decomposition of copper (II) carbonate is:

The green copper (II) carbonate
changes to black copper oxide 
Answer:
What is true of a solution of 1.0 M HCl(aq)? It contains 1.0 gram of HCl per 100 grams of water.
Explanation:
0 degree Celsius is equal to 272 k
So to convert C to k we need to add 273
To convert K to C we need to subtract 273