Page 66 - Chemistry ICSE Class IX

54 ICSE Chemistry – 9

Ans. Fuel %CNQTKſE XCNWG Ignition temperature Products of combustion
A 80 kJ/g 20°C CO , SO and SO 3
2
2
B 60 kJ/g 100°C H O, CO 2
2
Fuel B, although has a lower calori c value, its ignition temperature is well above the room temperature. The
products of combustion of B are less polluting as compared to that of the fuel A. Therefore, fuel B is better than
fuel A.

ASSIGNMENT 3

Combustion, Conditions essential for combustion,
Respiration and Combustion, Oxygen-Carbon dioxide balance in nature

ϭ͘ tŚĂƚ ŝƐ ĐŽŵďƵƐƟŽŶ͍
Ϯ͘ EĂŵĞ ƚŚĞ ŵŽƐƚ ĐŽŵŵŽŶ ƐƵƉƉŽƌƚĞƌ ŽĨ ĐŽŵďƵƐƟŽŶ͘ ĂŶ ĐŽŵďƵƐƟŽŶ ƚĂŬĞ ƉůĂĐĞ ŝŶ ƚŚĞ ĂďƐĞŶĐĞ ŽĨ Ăŝƌ Žƌ ŽdžLJŐĞŶ͍ 'ŝǀĞ
ƐƵŝƚĂďůĞ ĞdžĂŵƉůĞ͘
ϯ͘ tŚLJ ĚŽĞƐ ƉĂƉĞƌ ďƵƌŶ ǁŝƚŚ Ă LJĞůůŽǁ ŇĂŵĞ͍
ϰ͘ ƉĞƌĨŽƌĂƚĞĚ ƐŚĞĞƚ ŝƐ ŬĞƉƚ ĂƌŽƵŶĚ ƚŚĞ ǁŝĐŬƐ ŝŶ Ă ŬĞƌŽƐĞŶĞ ǁŝĐŬ ƐƚŽǀĞ͘ tŚLJ͍
ϱ͘ tŚĂƚ ŝƐ ƚŚĞ ŶĂŵĞ ŐŝǀĞŶ ƚŽ ƚŚĞ ŵŝŶŝŵƵŵ ƚĞŵƉĞƌĂƚƵƌĞ ƵƉ ƚŽ ǁŚŝĐŚ Ă ƐƵďƐƚĂŶĐĞ ƐŚŽƵůĚ ďĞ ŚĞĂƚĞĚ ďĞĨŽƌĞ ŝƚ ĐĂŶ ĐĂƚĐŚ ƟƌĞ͍
ϲ͘ tŚLJ ĚŽĞƐ Ă ŵĂƚĐŚƐƟĐŬ ŶŽƚ ĐĂƚĐŚ ĮƌĞ ŽŶ ŝƚƐ ŽǁŶ͍
ϳ͘ tŚLJ ĚŽĞƐ Ă ŚĞĂƉ ŽĨ ĐŽĂů Žƌ ǁŽŽĚ ŶŽƚ ĐĂƚĐŚ ĮƌĞ Ăƚ ƌŽŽŵ ƚĞŵƉĞƌĂƚƵƌĞ ƚŚŽƵŐŚ ƐƵĸĐŝĞŶƚ ƋƵĂŶƟƚLJ ŽĨ ŽdžLJŐĞŶ ŝƐ ƉƌĞƐĞŶƚ ŝŶ
ƚŚĞ Ăŝƌ͍
ϴ͘ tŚLJ ĚŽĞƐ Ă phuljhari ;ƐƉĂƌŬŝŶŐ ůŝŐŚƚ ĐƌĂĐŬĞƌͿ ƌĞƋƵŝƌĞ ƐŽŵĞ ŚĞĂƟŶŐ ďĞĨŽƌĞ ŝƚ ƐƉĂƌŬƐ͍
ϵ͘ tŚLJ ĚŽĞƐ ƉĞƚƌŽůĞƵŵ ďƵƌŶ ĨĂƐƚĞƌ ƚŚĂŶ ĐŽĂů͍
ϭϬ͘ tŚŝĐŚ ŚĂƐ ůŽǁĞƌ ŝŐŶŝƟŽŶ ƚĞŵƉĞƌĂƚƵƌĞ ʹ ƉĞƚƌŽů Žƌ ŬĞƌŽƐĞŶĞ Žŝů͍
ϭϭ͘ tŚŝĐŚ ŚĂƐ Ă ůŽǁĞƌ ŝŐŶŝƟŽŶ ƚĞŵƉĞƌĂƚƵƌĞ ʹ ŬĞƌŽƐĞŶĞ Žƌ >W'͍
ϭϮ͘ EĂŵĞ ƚŚĞ ƉƌŽĐĞƐƐ ďLJ ǁŚŝĐŚ ƚŚĞ ĚŝŐĞƐƚĞĚ ĨŽŽĚ ŝƐ ŽdžŝĚŝƐĞĚ ŝŶ ŽƵƌ ďŽĚLJ͘
ϭϯ͘ tŚLJ ŝƐ ƌĞƐƉŝƌĂƟŽŶ ĐĂůůĞĚ ƐůŽǁ ĐŽŵďƵƐƟŽŶ͍

Let us Answer Some More Questions

1. Distinguish between physical and chemical changes.
2. Why is rusting of iron considered a chemical change?
3. What are the conditions necessary for a chemical reaction to take place?
4. What is a displacement reaction? Give an example to describe it.
5. What is a precipitation reaction? Give two examples of this.
'
6. What type of reaction is the reaction CaCO (s) o CaO(s) + CO (g)?
3
2
7. Name the reaction in which one of the reacting species loses while the other gains electrons.
8. Name one each of the following:
(a) combustible substance (b) noncombustible substance (c) supporter of combustion.
9. What are the conditions necessary for the combustion to take place?
10. Why is partial combustion dangerous?
11. What is the usefulness of photosynthesis for those living on the earth?
12. Complete the following equations and state in each case, if the reaction represents oxidation or reduction.
–
3+
2+
(a) Fe o Fe (b) Cl o Cl (c) Cu o Cu 2+
+
3+
(d) Ag o Ag (e) H o H + (f) Al o Al
13. Mention the characteristics of a chemical change.