Mass fraction of sulfur and oxygen in the crust are respectively
0.52 and 0.295. how many times is the number of oxygen atoms in the earth's crust
more sulfur atoms?

First, we divide the mass fraction of each element by their corresponding molar mass:
0.52 / 32.1 = 0.0162
0.285 / 16 = 0.0184

Next, we simply divide the values that we get:
0.0184/0.0162 = 1.14

So, the there are 1.14 times more oxygen atoms than sulfur atoms in the Earth's crust.