 # NCERT Exemplar Solutions Class 9 Science Solutions for Structure of the Atom - Exercise in Chapter 4 - Structure of the Atom

Question 47 Structure of the Atom - Exercise

In the Gold foil experiment of Geiger and Marsden, which paved the way for Rutherford’s model of an atom, ~ 1.00% of the α-particles were found to deflect at angles > 50º. If one mole of α-particles were bombarded on the gold foil, compute the number of α-particles that would deflect at angles less than 500.

Total number of α particles used for bombardment = 1 mole

1 mole=6.022×1023 particle

number of α particles deflected at angles greater than 50°(>50°)= 1%

Number of α particles deflected at angles greater than 50° = 100-1 = 99%

The actual number of α particles deflected at angles less than 50°= 99/100 × 6.022 × 1023

=5.96 × 1023

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