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4. d and f- block elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistry4. d and f- block elements1 Mark
MCQ
Which of the statements is not true?
  • A
    On passing $H_2S$ through acidified $K_2Cr_2O_7$ solution, a milky colour is observed.
  • ✓
    $Na_2Cr_2O_7$ is preferred over $K_2Cr_2O_7$ in volumetric analysis.
  • C
    $K_2Cr_2O_7$ solution in acidic medium is orange.
  • D
    $K_2Cr_2O_7$ solution becomes yellow on increasing the $pH$ beyond $7$
✓

Answer

Correct option: B.
$Na_2Cr_2O_7$ is preferred over $K_2Cr_2O_7$ in volumetric analysis.
b
Nylon $- 66$ is a fibre as in it the forces of attraction are $H-$ bonding not a elastomer.

All other given statements are true.

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