Question

If the diameter of a carbon atom is 0.15 nm, calculate the number of carbon atoms which can be placed side by side in a straight line across length of scale of length 20 cm long.

Answer 1

1 m = 100 cm 1 cm
= 102 m
Length of the scale = 20 cm = 20 × 102 m
Diameter of a carbon atom = 0.15 nm = 0.15 × 109 m
One carbon atom occupies 0.15 × 109 m.
∴ Number of carbon atoms that can be placed in a straight line
= $\frac{20\times 106^{-2}\,m}{0.15\times 10^{-9}\,m}$
= 133.33 × 107
= 1.33 × 109