120. The sudden fall of atmospheric pressure indicates miltimeters is used to measure?
121. Hydrogen spectrum was first explained by
122. Magnetism in materials is due to?
A.electrons at rest
B.circular motion of electrons
C.protons at rest
D.all neutrons at rest
123. 'Short-sight' in human eye can be corrected by using proper
124. What is the reason for twinkling of stars?
A.Dispersion of light
B.Total internal reflection
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