kak tolong bantuin besok harus wajib kumpul

2.
a) Pb + PbO2 + 2H2SO4 -> 2PbSO4 + 2H2O
b) 2NH3 + 5/2O2 -> 2NO + 3H2O
c) CO + ½O2 -> CO2
d) Na + H2O -> NaOH + ½H2
e) ½Cl2 + KI -> KCl + ½I2

3.
a) Na2SO4: 46 + 32 + 64 = 142
b) KMnO4: 39 + 54 + 64 = 157
c) Ba(NO3)2 × 2H2O: 137 + 28 + 96 + 4 + 32 = 297

4.
a) 25 gram NaCl (Mr: 58.5)
m = gr/mr
m= 25/58.5
m = 0.4

b) 3.01×10^24 air/H2O
n = m × L
m = n/L
m = 3.01×10^24/6.02×10^23
m = 5

c) 50 liter air/H2O (STP)
V = m × 22.4 (STP)
m = V/22.4
m = 50/22.4
m = 2.2