The dand fblock elements - Result Question 48
####48. Which of the statements is not true? [2012]
(a) On passing $H_2 S$ through acidified $K_2 Cr_2 O_7$ solution, a milky colour is observed.
(b) $Na_2 Cr_2 O_7$ is preferred over $K_2 Cr_2 O_7$ in volumetric analysis.
(c) $K_2 Cr_2 O_7$ solution in acidic medium is orange.
(d) $K_2 Cr_2 O_7$ solution becomes yellow on increasing the $pH$ beyond 7 .
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Solution:
(b) $Na_2 Cr_2 O_7$ is hygroscopic in nature and therefore accurate weighing is not possible in normal atmospheric conditions. A hygroscopic substance absorbs moisture from atmosphere and this could lead to inaccuracies in weight.
