{"segment":[{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" M\u1ed9t dung d\u1ecbch c\u00f3 ch\u1ee9a 75 gam ${{K}_{2}}S{{O}_{4}}$ trong 1500 gam dung d\u1ecbch thu \u0111\u01b0\u1ee3c dung d\u1ecbch c\u00f3 n\u1ed3ng \u0111\u1ed9 ph\u1ea7n tr\u0103m l\u00e0:","select":["A. 1 % ","B. 4,76 %","C. 5 % ","D. 7 %"],"hint":"","explain":"<span class='basic_left'>$C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{75}{1500}.100\\%=5\\%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2440},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" H\u00f2a tan 1 mol $KCl$ trong 750 ml dung d\u1ecbch thu \u0111\u01b0\u1ee3c n\u1ed3ng \u0111\u1ed9 $KCl$ l\u00e0:","select":["A. 1,33 M ","B. 1,5 M","C. 1,75 M ","D. 2 M"],"hint":"","explain":"<span class='basic_left'>${{C}_{M}}=\\dfrac{n}{V}=\\dfrac{1}{0,75}\\approx 1,33\\,M$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2441},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" N\u1ed3ng \u0111\u1ed9 mol c\u1ee7a dung d\u1ecbch ch\u1ee9a 400 gam $CuS{{O}_{4}}$ trong 4 l\u00edt dung d\u1ecbch l\u00e0:","select":["A. 0,625 M","B. 1,5 M","C. 1,75 M","D. 2 M"],"hint":"","explain":"<span class='basic_left'>$\\begin{aligned} & {{n}_{CuS{{O}_{4}}}}=\\dfrac{400}{160}=2,5\\,mol \\\\ & {{C}_{M}}=\\dfrac{n}{V}=\\dfrac{2,5}{4}=0,625M \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2442},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" H\u00f2a tan 32 gam $NaN{{O}_{3}}$trong 2 kg dung d\u1ecbch thu \u0111\u01b0\u1ee3c dung d\u1ecbch c\u00f3 n\u1ed3ng \u0111\u1ed9 ph\u1ea7n tr\u0103m l\u00e0:","select":["A. 1 %","B. 1,2 %","C. 1,6 % ","D. 2 %"],"hint":"","explain":"<span class='basic_left'>$C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{32}{2000}.100\\%=1,6\\%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2443},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" \u0110\u1ec3 pha ch\u1ebf 0,5 l\u00edt dung d\u1ecbch $NaCl$ 0,9 M c\u1ea7n l\u1ea5y s\u1ed1 gam $NaCl$ l\u00e0:","select":["A. 23,25 gam","B. 25,26 gam","C. 26,325 gam","D. 27,62 gam"],"hint":"","explain":"<span class='basic_left'>$\\begin{aligned} & {{n}_{NaCl}}={{C}_{M}}.V=0,5.0,9=0,45\\,mol \\\\ & \\Rightarrow {{m}_{NaCl}}=0,45.58,5=26,325\\,gam \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2444},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" \u0110\u1ec3 pha ch\u1ebf 50 gam dung d\u1ecbch $MgC{{l}_{2}}$ 4% c\u1ea7n l\u1ea5y s\u1ed1 gam $MgC{{l}_{2}}$ l\u00e0:","select":["A. 1 gam ","B. 1,5 gam","C. 2 gam ","D. 2,6 gam"],"hint":"","explain":"<span class='basic_left'> $C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%\\Rightarrow {{m}_{ct}}=\\dfrac{C\\%.{{m}_{\\text{dd}}}}{100\\%}=\\dfrac{4\\%.50}{100\\%}=2\\,gam$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2445},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" \u1ede ${{25}^{0}}C$ \u0111\u1ed9 tan c\u1ee7a mu\u1ed1i \u0103n l\u00e0 36 gam. N\u1ed3ng \u0111\u1ed9 ph\u1ea7n tr\u0103m c\u1ee7a dung d\u1ecbch mu\u1ed1i \u0103n b\u00e3o h\u00f2a l\u00e0:","select":["A. 15,72 % ","B. 21,64 % ","C. 26,47 %","D. 27,9 % "],"hint":"","explain":"<span class='basic_left'>\u1ede ${{25}^{0}}C$ \u0111\u1ed9 tan c\u1ee7a mu\u1ed1i \u0103n l\u00e0 36 gam $\\Rightarrow {{m}_{ct}}=36\\,gam;\\,{{m}_{\\text{dd}}}=36+100=136\\,gam$ $\\Rightarrow C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{36}{136}.100\\%\\approx 26,47\\%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2446},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" \u1ede ${{25}^{0}}C$ \u0111\u1ed9 tan c\u1ee7a \u0111\u01b0\u1eddng l\u00e0 204 gam. N\u1ed3ng \u0111\u1ed9 ph\u1ea7n tr\u0103m c\u1ee7a dung d\u1ecbch \u0111\u01b0\u1eddng b\u00e3o h\u00f2a l\u00e0:","select":["A. 72 % ","B. 64 %","C. 67 %","D. 79 %"],"hint":"","explain":"<span class='basic_left'>\u1ede ${{25}^{0}}C$ \u0111\u1ed9 tan c\u1ee7a \u0111\u01b0\u1eddng l\u00e0 204 gam $\\Rightarrow {{m}_{ct}}=204\\,gam;\\,{{m}_{\\text{dd}}}=204+100=304\\,gam$ <br\/> $\\Rightarrow C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{204}{304}.100\\%\\approx 67\\%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2447},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" \u0110\u1ec3 pha \u0111\u01b0\u1ee3c 200 gam dung d\u1ecbch $BaC{{l}_{2}}$ 5% ta c\u1ea7n:","select":["A. H\u00f2a tan 190 gam $BaC{{l}_{2}}$ trong 10 gam ${{H}_{2}}O$ ","B. H\u00f2a tan 10 gam $BaC{{l}_{2}}$ trong 190 gam ${{H}_{2}}O$ ","C. H\u00f2a tan 100 gam $BaC{{l}_{2}}$ trong 100 gam ${{H}_{2}}O$ ","D. H\u00f2a tan 10 gam $BaC{{l}_{2}}$ trong 200 gam ${{H}_{2}}O$ "],"hint":"","explain":"<span class='basic_left'>${{m}_{ct}}=\\dfrac{{{m}_{\\text{dd}}}.C\\%}{100\\%}=\\dfrac{200.5\\%}{100\\%}=10\\,gam\\Rightarrow {{m}_{{{H}_{2}}O}}=200-10=190\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2448},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" H\u00f2a tan 20 gam $KN{{O}_{3}}$ v\u00e0o 850 ml n\u01b0\u1edbc thu \u0111\u01b0\u1ee3c dung d\u1ecbch c\u00f3 n\u1ed3ng \u0111\u1ed9 l\u00e0 (coi th\u1ec3 t\u00edch dung d\u1ecbch kh\u00f4ng thay \u0111\u1ed5i)","select":["A. 0,233 M","B. 23,3 M","C. 2,33 M ","D. 233M"],"hint":"","explain":"<span class='basic_left'>$\\begin{aligned} & {{n}_{KN{{O}_{3}}}}=\\dfrac{20}{101}\\approx 0,198\\,mol \\\\ & {{C}_{M\\,}}=\\dfrac{n}{V}=\\dfrac{0,198}{0,85}\\approx 0,233\\,M \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2449},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" Khi l\u00e0m bay h\u01a1i 50g m\u1ed9t dung d\u1ecbch mu\u1ed1i th\u00ec thu \u0111\u01b0\u1ee3c 0,5g mu\u1ed1i khan. H\u1ecfi l\u00fac \u0111\u1ea7u, dung d\u1ecbch c\u00f3 n\u1ed3ng bao nhi\u00eau ph\u1ea7n tr\u0103m:","select":["A. 1,1 % ","B. 1 %","C. 1,5 % ","D. 3 %"],"hint":"","explain":"<span class='basic_left'>$\\Rightarrow C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{0,5}{50}.100\\%=1\\%$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2450},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" Mu\u1ed1n pha 300ml dung d\u1ecbch $NaCl$ 3M th\u00ec kh\u1ed1i l\u01b0\u1ee3ng $NaCl$ c\u1ea7n l\u1ea5y l\u00e0:","select":["A. 52,65g ","B. 54,65g","C. 60,12g ","D. 60,18g"],"hint":"","explain":"<span class='basic_left'>${{n}_{NaCl}}={{C}_{M}}.V=3.0,3=0,9\\,mol\\Rightarrow {{m}_{NaCl}}=0,9.58,5=52,65\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2451},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" C\u00f3 50 gam dung d\u1ecbch ${{H}_{2}}S{{O}_{4}}$ 20% c\u1ea7n th\u00eam l\u01b0\u1ee3ng n\u01b0\u1edbc l\u00e0 bao nhi\u00eau \u0111\u1ec3 thu \u0111\u01b0\u1ee3c dung d\u1ecbch c\u00f3 n\u1ed3ng \u0111\u1ed9 % l\u00e0 15%","select":["A. 10,5 gam ","B. 13,7 gam","C. 16,67 gam ","D. 18,9 gam"],"hint":"","explain":"<span class='basic_left'>G\u1ecdi x l\u00e0 l\u01b0\u1ee3ng n\u01b0\u1edbc c\u1ea7n th\u00eam <br\/> ${{m}_{{{H}_{2}}S{{O}_{4}}}}=\\dfrac{50.20\\%}{100\\%}=10\\,gam$. Khi th\u00eam m gam n\u01b0\u1edbc th\u00ec ${{m}_{\\text{dd}}}=50+x$ <br\/> $C\\%=\\dfrac{{{m}_{ct}}}{{{m}_{\\text{dd}}}}.100\\%=\\dfrac{10}{50+x}.100\\%=15\\%\\Rightarrow x\\approx 16,67\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2452},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" Mu\u1ed1n pha 300g dung d\u1ecbch $NaCl$ 20% th\u00ec kh\u1ed1i l\u01b0\u1ee3ng $NaCl$ c\u1ea7n c\u00f3 l\u00e0:","select":["A. 40g ","B. 50g","C. 60g","D. 70g"],"hint":"","explain":"<span class='basic_left'>${{m}_{NaCl}}=\\dfrac{{{m}_{\\text{dd}}}.C\\%}{100\\%}=\\dfrac{300.20\\%}{100\\%}=60\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2453},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" Mu\u1ed1n pha 300g dung d\u1ecbch $NaCl$ 20% th\u00ec: Kh\u1ed1i l\u01b0\u1ee3ng ${{H}_{2}}O$c\u1ea7n c\u00f3 l\u00e0:","select":["A. 480g","B. 506g","C. 360g ","D. 240g "],"hint":"","explain":"<span class='basic_left'>${{m}_{NaCl}}=\\dfrac{{{m}_{\\text{dd}}}.C\\%}{100\\%}=\\dfrac{300.20\\%}{100\\%}=60\\,gam\\Rightarrow {{m}_{{{H}_{2}}O}}=300-60=240\\,gam$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2454},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" Mu\u1ed1n pha 150g dung d\u1ecbch $CuS{{O}_{4}}$ 2% t\u1eeb dung d\u1ecbch$~CuS{{O}_{4}}$ 20% th\u00ec kh\u1ed1i l\u01b0\u1ee3ng dung d\u1ecbch $~CuS{{O}_{4}}$ 20% c\u1ea7n l\u1ea5y l\u00e0:","select":["A. 14g ","B. 15g","C. 16g ","D. 17g"],"hint":"","explain":"<span class='basic_left'>Dung d\u1ecbch ban \u0111\u1ea7u c\u00f3: ${{m}_{CuS{{O}_{4}}}}=\\dfrac{{{m}_{\\text{dd}}}.C\\%}{100\\%}=\\dfrac{150.2\\%}{100\\%}=3\\,gam$. <br\/> Ta pha t\u1eeb dung d\u1ecbch $~CuS{{O}_{4}}$20\\% n\u00ean kh\u1ed1i l\u01b0\u1ee3ng $~CuS{{O}_{4}}$ kh\u00f4ng \u0111\u1ed5i $\\Rightarrow {{m}_{\\text{dd}\\,{{H}_{2}}S{{O}_{4}}\\,20\\%}}=\\dfrac{{{m}_{ct}}.100\\%}{C\\%}=\\dfrac{3.100\\%}{20\\%}=15\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2455},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" Mu\u1ed1n pha 150g dung d\u1ecbch $~CuS{{O}_{4}}$ 2% t\u1eeb dung d\u1ecbch $~CuS{{O}_{4}}$ 20% th\u00ec kh\u1ed1i l\u01b0\u1ee3ng n\u01b0\u1edbc c\u1ea7n l\u1ea5y l\u00e0:","select":["A. 140g ","B. 150g","C. 135g ","D. 137g"],"hint":"","explain":"<span class='basic_left'>Dung d\u1ecbch ban \u0111\u1ea7u c\u00f3: ${{m}_{CuS{{O}_{4}}}}=\\dfrac{{{m}_{\\text{dd}}}.C\\%}{100\\%}=\\dfrac{150.2\\%}{100\\%}=3\\,gam$. <br\/> Ta pha t\u1eeb dung d\u1ecbch $~CuS{{O}_{4}}$ 20 % n\u00ean kh\u1ed1i l\u01b0\u1ee3ng $~CuS{{O}_{4}}$ kh\u00f4ng \u0111\u1ed5i $\\Rightarrow {{m}_{\\text{dd}\\,{{H}_{2}}S{{O}_{4}}\\,20\\%}}=\\dfrac{{{m}_{ct}}.100\\%}{C\\%}=\\dfrac{3.100\\%}{20\\%}=15\\,gam\\Rightarrow {{m}_{{{H}_{2}}O}}=150-15=135\\,gam$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2456},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" Pha lo\u00e3ng 20g dung d\u1ecbch ${{H}_{2}}S{{O}_{4}}$ n\u1ed3ng \u0111\u1ed9 50% \u0111\u1ec3 \u0111\u01b0\u1ee3c 50g dung d\u1ecbch. Dung d\u1ecbch sau khi pha lo\u00e3ng c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng ri\u00eang d = 1,08g\/ml. N\u1ed3ng \u0111\u1ed9 mol c\u1ee7a dung d\u1ecbch l\u00e0:","select":["A. 2,2 M ","B. 1,2 M","C. 1,84 M ","D. 2,5 M"],"hint":"","explain":"<span class='basic_left'>Khi pha lo\u00e3ng dung d\u1ecbch ta c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng ch\u1ea5t tan kh\u00f4ng \u0111\u1ed5i <br\/> $\\begin{aligned} & {{m}_{{{H}_{2}}S{{O}_{4}}}}=\\dfrac{20.50\\%}{100\\%}=10\\,gam\\Rightarrow {{n}_{{{H}_{2}}S{{O}_{4}}}}=\\dfrac{10}{98}\\approx 0,1\\,02mol \\\\ & {{V}_{\\text{dd}}}=\\dfrac{m}{d}=\\dfrac{50}{1,08}\\approx 46,3\\,ml=0,0463\\,L\\Rightarrow {{C}_{M\\,\\text{dd}}}=\\dfrac{n}{V}=\\dfrac{0,102}{0,0463}\\approx 2,2\\,M \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2457},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" Tr\u1ed9n 2 l\u00edt dung d\u1ecbch $HCl$ 4M v\u00e0o 1 l\u00edt dung d\u1ecbch $HCl$ 0,5M. N\u1ed3ng \u0111\u1ed9 mol c\u1ee7a dung d\u1ecbch m\u1edbi l\u00e0:","select":["A. 2,82M ","B. 2,81M ","C. 2,83M ","D. T\u1ea5t c\u1ea3 \u0111\u1ec1u sai"],"hint":"","explain":"<span class='basic_left'>T\u1ed5ng ${{n}_{HCl}}=2.4+1.0,5=8,5\\,mol$ <br\/> T\u1ed5ng ${{V}_{\\text{dd}}}=2+1=3\\,L\\Rightarrow {{C}_{M}}=\\dfrac{n}{V}=\\dfrac{8,5}{3}\\approx 2,83\\,M$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2458},{"time":24,"part":[{"title":"Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n \u0110\u00daNG","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" C\u00f3 50g dung d\u1ecbch $NaOH$ 20%. Kh\u1ed1i l\u01b0\u1ee3ng $NaOH$ c\u1ea7n cho th\u00eam v\u00e0o dung d\u1ecbch tr\u00ean \u0111\u1ec3 \u0111\u01b0\u1ee3c dung d\u1ecbch 25% l\u00e0:","select":["A. 3,33 g ","B. 5,2 g ","C. 6,4 g ","D. 7 g"],"hint":"","explain":"<span class='basic_left'>G\u1ecdi x l\u00e0 kh\u1ed1i l\u01b0\u1ee3ng $NaOH$c\u1ea7n th\u00eam <br\/> Ban \u0111\u1ea7u: ${{m}_{NaOH}}=\\dfrac{50.20\\%}{100\\%}=10\\,gam$ <br\/> Sau khi th\u00eam $NaOH\\Rightarrow {{m}_{\\text{dd}}}=50+x;\\,{{m}_{NaOH}}=10+x$ <br\/> N\u1ed3ng \u0111\u1ed9 % c\u1ee7a dung d\u1ecbch thu \u0111\u01b0\u1ee3c l\u00e0 25% $\\Rightarrow \\dfrac{10+x}{50+x}.100\\%=25\\%\\Rightarrow x\\approx 3,33$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2459}],"lesson":{"save":0,"level":2}}