Question

2 precautions while taking pH of samples

Answer 1

1. The substances should not be directly touched as they might have a corroisive nature.
2. Always the aqueous solution of the substance should be tested as substances do not ionise in dry state.

Hope it helped. Good luck.

Answer 2

1.    Use only the standard colour chart supplied with the pH paper for assessing the ph value.
2.    Keep the pH strips away from chemical fumes.
3.    Either use fresh fine dropper or glass rod for each different sample, or wash the dropper or rod well with water every time.