Answer:
9.96 × 10⁸
Explanation:
Step 1: Calculate the diameter of 1 aluminum atom
The diameter of a sphere is 2 times the radius.
d = 2 × 140 pm = 280 pm
Step 2: Convert "d" to m
We will use the conversion factor 1 m = 10¹² pm.
280 pm × 1 m/10¹² pm = 2.80 × 10⁻¹⁰ m
Step 3: Convert the total length (L) to m
We will use the conversion factor 1 m = 100 cm.
27.9 cm × 1 m/100 cm = 0.279 m
Step 4: Calculate the number of atoms of aluminum required
We will use the following expression.
L/d = 0.279 m/2.80 × 10⁻¹⁰ m = 9.96 × 10⁸
