Statement-I : Positive zero error is added in measurement.

Statement-II : Defect may occurs during manufacturing of measuring instruments.

To determine the correctness of the given statements, let us analyze the concept of zero error in measuring instruments step-by-step.

Analysis of Statement-I:
Zero error occurs when a measuring instrument displays a non-zero reading when the actual measured quantity is zero.
If the zero mark of the vernier scale (or circular scale) lies to the right of the main scale zero (or is ahead of the reference line), it is called positive zero error. In this case, the instrument reads more than the actual value.
To obtain the correct or true measurement, we must subtract the positive zero error from the observed reading:
True Reading = Observed Reading - (Positive Zero Error)
Therefore, positive zero error is subtracted from the measurement, not added. Thus, Statement-I is wrong.

Analysis of Statement-II:
Zero errors and other systematic errors in measuring instruments (like vernier calipers, screw gauges, etc.) are often defects that occur due to wear and tear or during the manufacturing process of the instruments. Thus, Statement-II is correct.

Conclusion:
Statement-I is wrong while statement-II is correct.