question_answer2)
Is burning of a candle wax a physical change or a chemical
change?
question_answer3)
Write difference between a physical change and a chemical
change.
question_answer4)
Which one is a chemical change-melting of iron or rusting
of iron?
question_answer5)
Give one use of quick lime.
question_answer6)
Give an example of double displacement reaction. (Write a
balanced equation only).
question_answer10)
What precaution should be taken while heating magnesium ribbon over
burner?
question_answer14)
Why do fire flies glow at night?
question_answer15)
Why is photosynthesis considered an endothermic reaction?
question_answer17)
Why should a magnesium ribbon be cleaned before burning in
air ?
question_answer24)
Why is combustion
of Liquified Petroleum Gas (LPG) a chemical change?
question_answer25)
Why should a
magnesium ribbon be cleaned before burning in air? [NCERT]
question_answer31)
Balance the
following chemical equation:
question_answer36)
Why is hydrogen
peroxide kept in coloured bottles?
question_answer39)
Why is
photosynthesis considered an endothennic reaction?
question_answer40)
What type of
reaction is represented by the digestion of food in our body?
question_answer46)
Why do we apply
paint on iron articles?
question_answer48)
Oil and fat
containing food items are flushed with nitrogen. Why? [NCERT]
question_answer51)
Define rancidity.
question_answer52)
Name one synthetic
antioxidant.
question_answer54)
How do we come to
know that a chemical reaction has taken place?
question_answer55)
Why respiration is
considered an exothermic reaction? Explain. [NCERT]
question_answer61)
What do you mean by
precipitation reactions? Explain with examples. [NCERT]
question_answer80)
What is the role of
a catalyst in a chemical reaction? [CBSE Delhi 2007]
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