Which of the following is a noncontact force? a. magnetic forces b. electrical forces c. gravitational forces d. all of these

a) Cr2(SO4)3(aq) + 3(NH4)2CO3(aq)  →  Cr2(CO3)3(s) + 3(NH4)2SO4(aq)

b) Ba(NO3)2(aq) + K2SO4(aq) → BaSO4(s) + 2KNO3(aq)

c) Fe(NO3)2(aq) + 2KOH(aq) → Fe(OH)2(s) +  2KNO3(aq)

Explanation:

a. Cr2(SO4)3(aq) + (NH4)2CO3(aq)

Cr2(SO4)3(aq) + 3(NH4)2CO3(aq)  →  2Cr^3+ + 3SO4^2- + 6NH4+ + 3CO3^2-

2Cr^3+ + 3SO4^2- + 6NH4+ + 3CO3^2- → Cr2(CO3)3 + 3(NH4)2SO4

Cr2(SO4)3(aq) + 3(NH4)2CO3(aq)  →  Cr2(CO3)3(s) + 3(NH4)2SO4(aq)

b. Ba(NO3)2(aq) + K2SO4(aq)

Ba(NO3)2(aq) + K2SO4(aq) → Ba2+ +2NO3- + 2K+ + SO4^2-

Ba2+ +2NO3- + 2K+ + SO4^2- → BaSO4 + 2KNO3

Ba(NO3)2(aq) + K2SO4(aq) → BaSO4(s) + 2KNO3(aq)

c. Fe(NO3)2(aq) + KOH(aq)

Fe(NO3)2(aq) + 2KOH(aq) → Fe^2+ + 2NO3- + 2K+ + 2OH-

Fe^2+ + 2NO3- + K+ + OH- → Fe(OH)2 +  2KNO3

Fe(NO3)2(aq) + 2KOH(aq) → Fe(OH)2(s) +  2KNO3(aq)