A 0.83-kg block is hung from and stretches a spring that is attached to the ceiling. A second block is attached to the first one, and the amount that the spring stretches from its unstretched length triples. What is the mass of the second block?

1.66 kg

Explanation:

Given that a 0.83-kg block is hung from and stretches a spring that is attached to the ceiling.

From Hook's law

F = Ke

But F = mg

Substitute mg for force in the Hook's law

Mg = ke

0.83 × 9.8 = ke

Make K the subject of formula

8.134 = Ke

K = 8.134 /e

Given that a second block is attached to the first one, and the amount that the spring stretches from its unstretched length triples.

That is

(0.83 + M) × 9.8 = K (3e)

Substitutes K into the above equation

(0.83 + M) × 9.8 = 8.134 / e (3e)

The e will cancel out

(0.83 + M) × 9.8 = 24.402

0.83 + M = 24.402/9.8

0.83 + M = 2.49

M = 2.49 - 0.83

M = 1.66 kg

Therefore, the mass of the second block is 1.66kg

whichever one it is, it's definitely not one that you included on the list you provided.