Q1. What happens chemically when quick lime is added to water?
Q2. How will you test for the gas which is liberated when HCL reacts with an active metal?
Q3. What is an oxidation reaction? Is it exothermic or endothermic? Give one example of oxidation Reaction.
Q4. Give an example of photochemical reaction.
Q5. Give an example of a decomposition reaction. Describe any activity to illustrate such a reaction by heating.
Q6. Why is respiration considered as exothermic process?
Q7. Balance the following chemical equation.
Fe(s) +H2O(g) = Fe3O4 + H2(g)
MnO2 + HCL = MnCl2 + Cl2 + H2O
HNO3 + Ca(OH)2 = Ca(NO3)2 + H2O
Q8. On what basis is a chemical equation balanced?
Q9. State any two observations in an activity suggesting the occurrence of a chemical reaction.
Q10. Name a reducing agent which may be used to obtain manganese from manganese dioxide.
Q11. What change in colour is observed when silver chloride is left exposed to sunlight? Also mention the type of chemical reaction.
Q12. Define a combination reaction. Give one example of an exothermic combination reaction.
Q13. What is observed when a solution of potassium iodide is added to lead nitrate solution?
What type of reaction is this? Write a balanced chemical equation for this reaction.
Q14. Distinguish between an exothermic and an endothermic reaction.
Q15. Distinguish between a displacement and a double displacement reaction.
Q16. Identify the type of reaction in the following:
Fe + CuSO4(aq) = FeSO4(aq) + Cu(s)
2H2 + O2 = 2H2O
Answers
Answer:
ans.1
When Calcium oxide i.e. quick lime is added to water filled in a bucket, it reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.
ans.2
When HCl reacts with an active metal,hydrogen gas is liberated. We can test the gas liberated by putting a candle in front of the mouth of the test tube where the gas is being liberated. Since hydrogen gas is flammable,it burns with a popping sound.
and.3
For example, when copper (Cu) is heated in the presence of air, it gets oxidised to form copper oxide (CuO). The chemical equation involved in this reaction can be represented as Since heat energy is absorbed in this process, this reaction is endothermic nature.
ans.4
Examples of photochemical reactions
Examples of photochemical reactionsPhotosynthesis:
plants use solar energy to convert carbon dioxide and water into glucose and oxygen. Human formation of vitamin D by exposure to sunlight. Bioluminescence: e.g. In fireflies, an enzyme in the abdomen catalyzes a reaction that produced light.
ans 5
Example of a decomposition reaction: When lead nitrate is heated in a test tube, it forms lead oxide, nitrogen dioxide and oxygen. white incolour in a test tube. Heat this test tube over a flame. ... Conclusion: Decomposition of lead nitrate is a thermal decomposition reaction.
ans 6
Respiration is considered as exothermic reaction because energy is released in this process. Glucose combines with oxygen present in our cells to form carbon dioxide and water along with energy. Hope This Helps You! Respiration is considered as exothermic reaction because energy is produced during this process.
ans 8
Chemical equation is balanced on the basis of law of conservation of mass ,i.e.number of atoms on the left side (reactants) should be equal to number of atoms on the right side (products). A Chemical equation is always balanced on comparison of number of atoms of each element on both sides of the reaction.
ans 9
In an activity, change in state and change in temperature indicate that a chemical reaction has taken place: eg. Calcium oxide reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.
ans 10
The reducing agent that can be used to obtain manganese from manganese dioxide is Aluminium powder.
ans 11
When white silver chloride is left exposed to sunlight then it turns black alongwith formation of Silver and Chlorine gas. i.e. Silver Chloride decomposes to form Silver and Chlorine gas.
ans 12
Combination reactions are always exothermic. For example barium metal and fluorine gas will combine in a highly exothermic reaction to form the salt barium fluoride: Another example is given by magnesium oxide combining with carbon dioxide: Often, reaction can fall into more than one category.
ans 13
When a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube, the precipitation of a yellowish solid is observed. This yellowish solid is lead iodide. Potassium nitrate is formed along with lead iodide.
ans 14
The difference between endothermic and exothermic reactions lies in the words themselves. "Thermic" refers to heat, just as in the word "thermometer." "Exo" means "outside" and "endo" means "inside." Thus, an endothermic reaction pulls heat into an object or area, while an exothermic reaction expels heat.
ans 15
In displacement reaction one element displaces another element from its compound and takes its place therein. ... Double displacement : The reaction in which the constituent atoms of the reaction interchange by the decomposition of the two reactants, to produce new compounds are called double displacement reactions.
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Answer:
Explanation:
ans.1
When Calcium oxide i.e. quick lime is added to water filled in a bucket, it reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.
ans.2
When HCl reacts with an active metal,hydrogen gas is liberated. We can test the gas liberated by putting a candle in front of the mouth of the test tube where the gas is being liberated. Since hydrogen gas is flammable,it burns with a popping sound.
and.3
For example, when copper (Cu) is heated in the presence of air, it gets oxidised to form copper oxide (CuO). The chemical equation involved in this reaction can be represented as Since heat energy is absorbed in this process, this reaction is endothermic nature.
ans.4
Examples of photochemical reactions
Examples of photochemical reactionsPhotosynthesis:
plants use solar energy to convert carbon dioxide and water into glucose and oxygen. Human formation of vitamin D by exposure to sunlight. Bioluminescence: e.g. In fireflies, an enzyme in the abdomen catalyzes a reaction that produced light.
ans 5
Example of a decomposition reaction: When lead nitrate is heated in a test tube, it forms lead oxide, nitrogen dioxide and oxygen. white incolour in a test tube. Heat this test tube over a flame. ... Conclusion: Decomposition of lead nitrate is a thermal decomposition reaction.
ans 6
Respiration is considered as exothermic reaction because energy is released in this process. Glucose combines with oxygen present in our cells to form carbon dioxide and water along with energy. Hope This Helps You! Respiration is considered as exothermic reaction because energy is produced during this process.
ans 8
Chemical equation is balanced on the basis of law of conservation of mass ,i.e.number of atoms on the left side (reactants) should be equal to number of atoms on the right side (products). A Chemical equation is always balanced on comparison of number of atoms of each element on both sides of the reaction.
ans 9
In an activity, change in state and change in temperature indicate that a chemical reaction has taken place: eg. Calcium oxide reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.
ans 10
The reducing agent that can be used to obtain manganese from manganese dioxide is Aluminium powder.
ans 11
When white silver chloride is left exposed to sunlight then it turns black alongwith formation of Silver and Chlorine gas. i.e. Silver Chloride decomposes to form Silver and Chlorine gas.
ans 12
Combination reactions are always exothermic. For example barium metal and fluorine gas will combine in a highly exothermic reaction to form the salt barium fluoride: Another example is given by magnesium oxide combining with carbon dioxide: Often, reaction can fall into more than one category.
ans 13
When a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube, the precipitation of a yellowish solid is observed. This yellowish solid is lead iodide. Potassium nitrate is formed along with lead iodide.
ans 14
The difference between endothermic and exothermic reactions lies in the words themselves. "Thermic" refers to heat, just as in the word "thermometer." "Exo" means "outside" and "endo" means "inside." Thus, an endothermic reaction pulls heat into an object or area, while an exothermic reaction expels heat.
ans 15
In displacement reaction one element displaces another element from its compound and takes its place therein. ... Double displacement : The reaction in which the constituent atoms of the reaction interchange by the decomposition of the two reactants, to produce new compounds are called double displacement reactions.
hope it will be helpful