A gold bar contains 5 moles of gold. How many atoms of gold are present in the bar?

= 3.01 x 10²³ atoms of gold (Au)

Explanation:

1 mole of any substance => 1 Avogadro's Number of particles = 6.02 x 10²³ particles.

∴ for 5 moles of gold atoms => 5 moles x 6.02 x 10²³ atoms/mole

= 3.01 x 10²³ atoms of gold (Au)

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

it's all four options.