$a,PTPƯ:Zn+2HCl\xrightarrow{} ZnCl_2+H_2↑$
$n_{Zn}=\dfrac{1,95}{65}=0,03mol.$
$Theo$ $pt:$ $n_{H_2}=n_{Zn}=0,03mol.$
$⇒V_{H_2}=0,03.22,4=0,672l.$
$b,Theo$ $pt:$ $n_{HCl}=2n_{Zn}=0,06mol.$
Đổi 150 ml = 0,15 lít.
$⇒CM_{HCl}=\dfrac{0,06}{0,15}=0,4M.$
$c,PTPƯ:2Al+6HCl\xrightarrow{} 2AlCl_3+3H_2↑$
$Theo$ $pt:$ $n_{Al}=\dfrac{2}{3}n_{H_2}=0,02mol.$
$⇒m_{Al}=0,02.27=0,54g.$
chúc bạn học tốt!