Which of these shows that a chemical
reaction has taken place?
a) change in state
b) evolution of gas
c) change in color
d) all of these
What is rust?
a) Sodium oxide
b) iron oxide
c) copper oxide
d) silver oxide
In glucose metabolism the pyruvate molecules may be fermented into:
a) ethanol
b) carbonic acid
c) lactic acid
d) none of these
A chemical reaction involves:
a) only breaking of bonds
b) only formation of bonds
c) both breaking and formation of bonds
d) none of these
Which among the following is not a chemical change?
a) melting of ice
b) soap making
c) rusting of iron
d) fermentation of substances
Re-treading is used for the recycling of:
a) car batteries
b) motor oils
c) tyres
d) metals
