1. Tardigrade
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  3. Chemistry
  4. When K2Cr2O7 is converted into K2CrO4 , the change in oxidation number of chromium is :

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Q. When $ K_2Cr_2O_7 $ is converted into $ K_2CrO_4 $ , the change in oxidation number of chromium is :

UPSEEUPSEE 2005

Solution:

The sum of oxidation state of all elements in a compound is always zero.

Let, oxidation state of $Cr$ in $K _{2} Cr _{2} O _{7}=x$

$(+1 \times 2)+2 x+(-2 \times 7)=0 $

or $+2+2 x-14=0$

$\therefore \, x=+6$

Let oxidation sate of $Cr$ in $K _{2} CrO _{4}=x$

$\therefore \,+1 \times 2+x+(-2 \times 4)=0$

$2+x-8=0 $

$\therefore \, x=6$

$\therefore $ Change in oxidation state of $Cr$ is zero when it changes from $K _{2} Cr _{2} O _{7}$ to $K _{2} CrO _{4}$