Which of the following is a precipitation reaction?
a. 2 lii(aq) +hg2(no3)2(aq) →hg2i2(s) + 2 lino3(aq)
b. nacl(aq) + lii(aq)→ nai(aq) + licl(aq)
c. hcl(aq) + koh(aq)→ kcl(aq) + h2o(l)
d. zn(s) + 2agno3(aq) → 2 ag(s) +zn(no3)2(aq)
e. none of the above areprecipitation reactions.

The precipitated are option a and d.

Explanation:

2 LiI(aq) +Hg2(NO3)2(aq)  →  Hg2I2(s) ↓ + 2 LiNO3(aq)

Cation Hg2+ 2 in the presence of iodide,  a precipitated  is formed.

Zn(s) + 2AgNO3(aq) → 2 Ag(s) ↓ +Zn(NO3)2(aq)

Zinc starts to get rid, and some white particles also stick to it. Afterwards the solution becomes cloudy and a precipitate appears, which is the solid silver

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )