A dish is given to you, which contains a blackish-yellow powder. When you move a magnet over it, black particles fly upwards and
get stuck to the magnet. All that's left in the dish is a yellow powder,
which you discover to be sulfur.

Ibelieve the answer is d. macula  hope my answer has you : )

Answerthe force between the charges will be  f/9 (one-ninth of force f)explanationcoulomb's law relates the magnitudes  two point charges q₁ and q₂, the distance, r, between the charges, and the electrostatic force, f, between the two charges:     k represents coulomb's constant, k = 8.99×10⁹ n·m²/c².note that if we have r = 3r, then   

Planck decided to assume that atoms could only vibrate at certain frequencies that were whole numbers eg 2f, 3f and so on. others used to think that atoms vibrate continuously