Which of the following reaction/s show/s endothermic reaction/s?
a) CaCO3(s) + heat -------àCaO(s) + CO2(g)
b) 2H2O2(l) +electricity-----à 2H2O(l) + O2(g)
c) 2H2(g) + O2(g) ---à 2H2O(g) + heat + light
d) both a and b
All endothermic reactions need a continuous source of ………
a) mass
b) gas
c) energy
d) air
What is required for exothermic reactions in the beginning of the process?
a) mass
b) gas
c) energy
d) air
Photosynthesis needs sunlight energy. What type of this reaction is?
a) addition
b) displacement
c) endothermic
d) exothermic
Ozone (O3)
absorbs UV rays in the upper atmosphere and converts into O2. What
type of this reaction is?
a) addition
b) displacement
c) endothermic
d) exothermic
Which of the following protects living things on the earth from UV radiation coming from the sun?
a) CO2
b) O2
c) O3
d) all of these
