Câu 1:

\(a,B=\left[\sqrt{a}-\dfrac{\left(\sqrt{a}+1\right)\left(a-\sqrt{a}+1\right)}{\sqrt{a}+1}\right]\left[\sqrt{a}+\dfrac{\left(\sqrt{a}-1\right)\left(a+\sqrt{a}+1\right)}{\sqrt{a}-1}\right]\\ B=\left(-a+2\sqrt{a}-1\right)\left(a+2\sqrt{a}+1\right)\\ B=-\left(\sqrt{a}-1\right)^2\left(\sqrt{a}+1\right)^2=-\left(a-1\right)^2\\ b,B=25\Leftrightarrow-\left(a-1\right)^2=25\left(\text{vô lí}\right)\\ \Leftrightarrow a\in\varnothing\)

thi ?

Bann ơi tôi xin đề trách nhiệm công nghệ đó với

Sao lại chụp đề thi? Đề thi bạn tự làm nha!

tk hen:

Câu 1:

a, \(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

b, \(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)

Theo PT: \(n_{H_2}=\dfrac{3}{2}n_{Al}=0,3\left(mol\right)\Rightarrow V_{H_2}=0,3.22,4=6,72\left(l\right)\)

c, \(n_{HCl}=3n_{Al}=0,6\left(mol\right)\)

\(\Rightarrow C\%_{HCl}=\dfrac{0,6.36,5}{200}.100\%=10,95\%\)

d, \(n_{AlCl_3}=n_{Al}=0,2\left(mol\right)\Rightarrow m_{AlCl_3}=0,2.133,5=26,7\left(g\right)\)