Atoms of different elements have
A). Same atomic number and same electronic configuration
B). Different atomic number and same eletronic configu-ration
C). Different atomic number and different number of valence electrons
D). Same number of electrons and neutrons
Which of the following is the maximum number of electrons that can be present in M-shell?
A). 2
B). 8
C). 18
D). 32
The depletion in Ozone layer is caused by ________ .
A). Nitrous oxide
B). Carbon dioxide
C). Chlorofluorocarbons
D). Methane
The smog is essentially caused by the presence of
A). O3 and N2
B). O2 and N2
C). Oxides of N and S
D). O2 and O3
Which of the following pollutants is main product of automobile exhaust ?
A). CO
B). CO2
C). NO
D). Hydrocarbons