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Câu hỏi: Phản ứng nào sau đây là sai
A. $Cr{{\left( OH \right)}_{3}}+NaOH\xrightarrow[{}]{{}}NaCr{{O}_{2}}+2{{H}_{2}}O$.
B. $Zn+2CrC{{l}_{3}}\xrightarrow[{}]{{}}ZnC{{l}_{2}}+2CrC{{l}_{2}}$.
C. $Cr+C{{l}_{2}}\xrightarrow[{}]{t{}^\circ }CrC{{l}_{2}}$.
D. $2N{{a}_{2}}Cr{{O}_{4}}+{{H}_{2}}S{{O}_{4}}\xrightarrow[{}]{{}}N{{a}_{2}}C{{r}_{2}}{{O}_{7}}+N{{a}_{2}}S{{O}_{4}}+{{H}_{2}}O$.
A. $Cr{{\left( OH \right)}_{3}}+NaOH\xrightarrow[{}]{{}}NaCr{{O}_{2}}+2{{H}_{2}}O$.
B. $Zn+2CrC{{l}_{3}}\xrightarrow[{}]{{}}ZnC{{l}_{2}}+2CrC{{l}_{2}}$.
C. $Cr+C{{l}_{2}}\xrightarrow[{}]{t{}^\circ }CrC{{l}_{2}}$.
D. $2N{{a}_{2}}Cr{{O}_{4}}+{{H}_{2}}S{{O}_{4}}\xrightarrow[{}]{{}}N{{a}_{2}}C{{r}_{2}}{{O}_{7}}+N{{a}_{2}}S{{O}_{4}}+{{H}_{2}}O$.
Phương trình phản ứng đúng là:
$2Cr+3C{{l}_{2}}\xrightarrow[{}]{{}}2CrC{{l}_{3}}$
$2Cr+3C{{l}_{2}}\xrightarrow[{}]{{}}2CrC{{l}_{3}}$
Đáp án C.