Q1. Why does copper not displace iron from iron sulphate solution?
Copper is less reactive than iron. A less reactive metal cannot displace a more reactive metal from its salt solution.
Q2. Why are carbon compounds generally poor conductors of electricity?
Most carbon compounds are covalent and do not have free ions or electrons to conduct electricity.
Q3. Why do we balance a chemical equation before using it?
To satisfy the law of conservation of mass, ensuring that the number of atoms of each element is equal on both sides of the equation.
Q4. Why is respiration considered an exothermic reaction?
Because glucose reacts with oxygen and releases energy in the form of heat.
Q5. Why does current increase when the resistance of a conductor is decreased?
According to Ohm's Law:
At constant voltage, current is inversely proportional to resistance. Therefore, when resistance decreases, current increases.
Q6. Why is the image formed by a concave mirror sometimes real and sometimes virtual?
The nature of the image depends on the object's position. If the object is beyond the focus, a real image is formed. If the object is between the focus and the mirror, a virtual image is formed.
Q7. Why is the human heart called a double pump?
Because its right side pumps deoxygenated blood to the lungs, while its left side pumps oxygenated blood to the rest of the body.
Q8. Why are acquired traits not inherited by offspring?
Acquired traits affect body cells but do not change the genes in reproductive cells, so they are not passed to offspring.
Q9. Why is the flow of energy in a food chain unidirectional?
Energy flows from the Sun → producers → consumers and is lost as heat at each level. It cannot return to the previous level.
Q10. Why should biodegradable waste not be mixed with non-biodegradable waste?
Because biodegradable waste can be decomposed and composted, while non-biodegradable waste cannot. Mixing them makes waste management and recycling difficult.
Exam-Oriented One-Liners
Copper is less reactive than iron.
Carbon compounds lack free ions/electrons.
To obey the law of conservation of mass.
Respiration releases heat energy.
Current increases when resistance decreases.
Image nature depends on object position.
Heart pumps blood in two separate circuits.
Acquired traits do not alter genes.
Energy flow is one-way and irreversible.
Separate disposal aids recycling and decomposition.
Copper is less reactive than iron. A less reactive metal cannot displace a more reactive metal from its salt solution.
Q2. Why are carbon compounds generally poor conductors of electricity?
Most carbon compounds are covalent and do not have free ions or electrons to conduct electricity.
Q3. Why do we balance a chemical equation before using it?
To satisfy the law of conservation of mass, ensuring that the number of atoms of each element is equal on both sides of the equation.
Q4. Why is respiration considered an exothermic reaction?
Because glucose reacts with oxygen and releases energy in the form of heat.
Q5. Why does current increase when the resistance of a conductor is decreased?
According to Ohm's Law:
At constant voltage, current is inversely proportional to resistance. Therefore, when resistance decreases, current increases.
Q6. Why is the image formed by a concave mirror sometimes real and sometimes virtual?
The nature of the image depends on the object's position. If the object is beyond the focus, a real image is formed. If the object is between the focus and the mirror, a virtual image is formed.
Q7. Why is the human heart called a double pump?
Because its right side pumps deoxygenated blood to the lungs, while its left side pumps oxygenated blood to the rest of the body.
Q8. Why are acquired traits not inherited by offspring?
Acquired traits affect body cells but do not change the genes in reproductive cells, so they are not passed to offspring.
Q9. Why is the flow of energy in a food chain unidirectional?
Energy flows from the Sun → producers → consumers and is lost as heat at each level. It cannot return to the previous level.
Q10. Why should biodegradable waste not be mixed with non-biodegradable waste?
Because biodegradable waste can be decomposed and composted, while non-biodegradable waste cannot. Mixing them makes waste management and recycling difficult.
Exam-Oriented One-Liners
Copper is less reactive than iron.
Carbon compounds lack free ions/electrons.
To obey the law of conservation of mass.
Respiration releases heat energy.
Current increases when resistance decreases.
Image nature depends on object position.
Heart pumps blood in two separate circuits.
Acquired traits do not alter genes.
Energy flow is one-way and irreversible.
Separate disposal aids recycling and decomposition.
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