1. 

$Cu+2H_2SO_4\to CuSO_4+SO_2+2H_2O$

$2Ag+2H_2SO_4\to Ag_2SO_4+SO_2+2H_2O$

$n_{NaOH}=0,07.0,5=0,035 mol$

- TH1: chất rắn chứa $NaOH$

Gọi x là mol $SO_2$

$SO_2+2NaOH\to Na_2SO_3+H_2O$

$\Rightarrow n_{Na_2SO_3}=x; n_{NaOH\text{dư}}=0,035-2x$ 

$\Rightarrow 40(0,035-2x)+126x=3,435$

$\Leftrightarrow x=0,044$

Gọi a, b là mol Ag, Cu.

$\Rightarrow 108a+64b=4,32$    (1)

$n_{SO_2}=0,5a+b=0,044$     (2)

(1)(2)$\Rightarrow a=0,02; b=0,034$

$\%m_{Ag}=50\%$

$\%m_{Cu}=50\%$

- TH2: chất rắn không chứa $NaOH$ 

Gọi m, n là mol $Na_2SO_3$, $NaHSO_3$

$2NaOH+SO_2\to Na_2SO_3+H_2O$

$NaOH+SO_2\to NaHSO_3$

$\Rightarrow 126m+104n=3,435$    (3)

$n_{NaOH}=2m+n=0,035$   (4)

(3)(4)$\Rightarrow m=0,0025; n=0,03$

$\Rightarrow n_{SO_2}=0,0025+0,03=0,0325 mol$ 

Gọi a, b là mol Cu, Ag.

$\Rightarrow 64a+108b=4,32$   (*)

$n_{SO_2}=a+0,5b=0,0325$  (**)

(*)(**)$\Rightarrow a=0,017; b=0,029$

$\%m_{Cu}=25,19\%$

$\%m_{Ag}=74,81\%$