Question

4. Lead oxide
d. red
Subjective Evaluation
E Answer the following questions:
1. What is a catalyst? What are the two types of catalysts? Give one example of each.
2. Define the following with one suitable example.
a. Exothermic reaction
b. Endothermic reaction
3. What is a chemical reaction? How is it represented? Explain with an example.
4. What are the characteristics of a chemical reaction? Make a list of them. Give one example each.
5. Explain with two examples where chemical reaction leads to formation of precipitate.
6. What are the two most essential conditions for a chemical reaction to take place? Give one
example of each
7. Write the word equations, one for each chemical reactions where the following conditions are
found:
a. evolution of
gas
b. contact in solution
use of pressure
d. use of electricity
use of heat
C.
e.
58
CHEMISTRY 7​

Answer 1

Answer:

$\huge\bold\pink{ANSWER :-}$

Examples of Exothermic Reactions

• any combustion reaction.
• a neutralization reaction.
• rusting of iron (rust steel wool with vinegar)
• the thermite reaction.
• reaction between water and calcium chloride.
• reaction between sodium sulfite and bleach (dilute sodium hypochlorite)
• reaction between potassium permanganate and glycerol.

• ===>>> reaction in which heat energy is liberated by the reactants is called exothermic reaction. eg: Carbon + Oxygen gives Carbon Dioxide + Q. reaction in which heat energy is absorbed by the reactants is called endothermic reaction. eg: Nitrogen + Oxygen gives 2 nitrous oxide (2NO) - Q.

====>>> Catalysts can be divided into two main types - heterogeneous and homogeneous. In a heterogeneous reaction, the catalyst is in a different phase from the reactants. In a homogeneous reaction, the catalyst is in the same phase as the reactants.

• ===>>> If you look at a mixture and can see a boundary between two of the components, those substances are in different phases. A mixture containing a solid and a liquid consists of two phases. A mixture of various chemicals in a single solution consists of only one phase, because you can't see any boundary between them.

Answer 2

Step-by-step explanation:

Examples of Exothermic Reactions

any combustion reaction.

a neutralization reaction.

rusting of iron (rust steel wool with vinegar)

the thermite reaction.

reaction between water and calcium chloride.

reaction between sodium sulfite and bleach (dilute sodium hypochlorite)

reaction between potassium permanganate and glycerol.

===>>> reaction in which heat energy is liberated by the reactants is called exothermic reaction. eg: Carbon + Oxygen gives Carbon Dioxide + Q. reaction in which heat energy is absorbed by the reactants is called endothermic reaction. eg: Nitrogen + Oxygen gives 2 nitrous oxide (2NO) - Q.

====>>> Catalysts can be divided into two main types - heterogeneous and homogeneous. In a heterogeneous reaction, the catalyst is in a different phase from the reactants. In a homogeneous reaction, the catalyst is in the same phase as the reactants.

===>>> If you look at a mixture and can see a boundary between two of the components, those substances are in different phases. A mixture containing a solid and a liquid consists of two phases. A mixture of various chemicals in a single solution consists of only one phase, because you can't see any boundary between them.