JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Pharmacy II PHARMACEUTICAL ANALYSIS-I Previous Question Paper (November/December - 2018 - R17)

0.1N Ceric ammonium sulphate is standardized by titration against a primary standard, typically Arsenic trioxide (As₂O₃). The titration is performed in an acidic medium (usually sulfuric acid) using ortho-phenanthroline ferrous sulphate (ferroin) as an indicator. The reaction involves the oxidation of As(III) to As(V) by Ce(IV), and the endpoint is marked by a sharp color change from red to pale blue.

Significant figures are the digits in a measured or calculated quantity that carry meaning regarding the precision of the measurement. They include all certain digits plus one uncertain or estimated digit at the end.

The rules for determining significant figures are:

1. All non-zero digits are significant.
2. Zeros between non-zero digits are always significant (e.g., 50.08 has four).
3. Leading zeros are never significant; they only indicate the position of the decimal point (e.g., 0.005 has one).
4. Trailing zeros in a number containing a decimal point are significant (e.g., 2.500 has four).
5. In whole numbers without a decimal, trailing zeros may or may not be significant depending on the context, though scientific notation is preferred to remove ambiguity.

In pharmaceutical analysis, maintaining the correct number of significant figures during calculations is essential to ensure that the final result does not imply a level of precision greater than that of the original experimental data.