Under what conditions heat can be given to a substance without raising its temperature?
When a mixture of iron powder and sulphur powder is heated strongly to form iron sulphide, then heat energy is :
(a) released (b) first absorbed and then released
(c) absorbed (d) neither absorbed nor released
Which of the following process / processes release heat ?
(i) condensation (ii) vaporisation (iii) freezing (iv) melting
(a) only (i) (b) only (iv) (c) (i) and (iii) (d) (ii) and (iv)
Give reasons for the following
1. Heating hydrated copper sulphate crystal is deemed a chemical change.
2. Efflorescence is minimum during humid conditions.
physical and chemical change
not a change
The reaction of Quicklime turning into Slaked Lime is
Exothermic, Blue Litmus Red
Endothermic, Blue litmus Red
Endothermic, Red litmus Blue
Exothermic, Red Litmus Blue
What do you observe when burning magnesium is lowered in a jar of CO2 ?
During combustion only dust is released.
Find the odd one out
Which among the following is an exothermic reaction?
All of the given options
Reaction during respiration
Melting solid salts
Burning of fuel is a/an
Which of the following is not a combustion reaction?
Boiling of water
Melting of wax
Burning of petrol.
Freezing of Ice
Write a non- exothermic reaction taking place in blast furnance during extraction of iron?
Reason: It is an exothermic reaction.
- Both assertion and reason are true and the reason is the correct explanation of assertion.
- Both assertion and reason are true but the reason is not the correct explanation of assertion.
- The assertion is true but the reason is false.
- Both assertion and reason are false.
The oxidation reactions which produce light and heat are known as _______________.
Respiration is an endothermic reaction.
Design an experiment to show that air contains water vapour. [3 MARKS]