Câu 2.

Nhiệt lượng bếp tỏa ra trong thời gian \(t=3min=180s\) là:

\(Q=UIt=RI^2t=60\cdot2,5^2\cdot180=675000J\)

Câu 3.

\(I_{Đ1}=\dfrac{U_{Đ1}}{R_{Đ1}}=\dfrac{6}{6}=1A\)

\(I_{Đ2}=\dfrac{U_{Đ2}}{R_{Đ2}}=\dfrac{1,5}{8}=\dfrac{3}{16}A\)

\(I_b=I_{Đ1}-I_{Đ2}=1-\dfrac{3}{16}=\dfrac{13}{16}A\)

\(R_b=\dfrac{U_b}{I_b}=\dfrac{1,5}{\dfrac{13}{16}}=\dfrac{24}{13}\Omega\)

\(n_{CaCO_3}=\dfrac{6}{100}=0,06mol\)

\(n_{CH_3COOH}=\dfrac{200}{60}=3,33mol\)

\(2CH_3COOH+CaCO_3\rightarrow\left(CH_3COO\right)_2Ca+CO_2+H_2O\)

       3,33        >     0,06                                                          ( mol )

                              0,06            0,06                     0,06             ( mol )

\(V_{CO_2}=0,06.22,4=1,344l\)

\(m_{\left(CH_3COO\right)_2Ca}=0,06.158=9,48g\)

\(m_{ddspứ}=200+6-0,06.12=205,28g\)

\(C\%_{\left(CH_3COO\right)_2Ca}=\dfrac{9,48}{205,28}.100=4,61\%\)

\(n_{CaCO_3}=\dfrac{6}{100}=0,06\left(mol\right)\\ n_{CH_3C\text{OO}H}=\dfrac{200}{60}=3,3\left(G\right)\\ pthh:CaCO_3+2CH_3C\text{OO}H\rightarrow Ca\left(CH_3C\text{OO}\right)_2+H_2O+CO_2\) 
LTL : \(\dfrac{0,06}{1}< \dfrac{3,3}{2}\) 
=> CaCO3 hết 
theo pthh : \(n_{CO_2}=n_{CaCO_3}=0,06\left(mol\right)\) 
\(\Rightarrow V_{CO_2}=0,06.22,4=1,344\left(l\right)\) 
\(\Rightarrow C\%=\dfrac{6}{200}.100\%=3\%\dfrac{\dfrac{ }{ }C\dfrac{ }{ }\dfrac{ }{ }\dfrac{ }{ }\dfrac{ }{ }}{ }\%\)

bài 1: 

\(\left\{{}\begin{matrix}x+y=57\\4x-2y=6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x+4y=228\\4x-2y=6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}6y=234\\x+y=57\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=39\\x=18\end{matrix}\right.\)

sao có ai 

sai đề à

ai=ab đó

a: \(\Leftrightarrow\left\{{}\begin{matrix}3x+6y=4\\x+4y=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{1}{3}\\x=\dfrac{2}{3}\end{matrix}\right.\)