First write the molecular equation with states:
(NH4)2S (aq) + 2AgNO3(aq) → Ag2S (s) + 2NH4NO3
Now write a full ionic equation by separating into ions all substances that dissociate: anything (s) (g) or (l) does not dissociate
2NH4 + (aq) + S 2-(aq) + 2Ag+ (aq) + 2NO3- (aq) → Ag2S(s) + 2NH4 + (aq) + 2NO3- (aq)
To write the NET IONIC equation, inspect the full ionic equation above and delete anything that appears on both sides of the → sign:
Net ionic equation:
S 2-(aq) + 2Ag + (aq) → Ag2S(s)
Answer:
a. The second run will be faster.
d. The second run has twice the surface area.
Explanation:
The rate of a reaction is proportional to the surface area of a catalyst. Given the volume (V) of a sphere, we can find its surface area (A) using the following expression.

The area of the 10.0 cm³-sphere is:

The area of each 1.25 cm³-sphere is:

The total area of the 8 1.25cm³-spheres is 8 × 5.61 cm² = 44.9 cm²
The ratio of 8 1.25cm³-sphere to 10.0 cm³-sphere is 44.9 cm²/22.4 cm² = 2.00
Since the surface area is doubled, the second run will be faster.
I think it is C. coefficients but I don't know what subscripts are