Answer: 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Precipitation is a type of displacement reaction in which one the products is formed in the solid state.
Answer:
3. A catalyst can convert an endothermic reaction into an exothermic reaction.
Explanation:
<em>What is NOT true for a catalyst? </em>
<em>1. A catalyst increases the rate of a chemical reaction by decreasing activation energy.</em> TRUE. A positive catalyst increases the reaction rate by decreasing the activation energy.
<em>2. A catalyst is not consumed in chemical reactions.</em> TRUE. A catalyst is recovered unaltered at the end of the reaction.
<em>3. A catalyst can convert an endothermic reaction into an exothermic reaction.</em> FALSE. A catalyst cannot modify the enthalpy of a reaction.
<em>4. A catalyst may be used in the solid, liquid or gaseous phase.</em> TRUE. If the catalyst is in the same phase as the reaction, the catalysis is homogeneous. Else, the catalysis is heterogeneous.
Units?
CO2 (s) and CO2 (g)
