Question

before dispensing 9 ml after dispensing a 5 ml b 4 ml which pipette above shows that 4 ml of liquid has been dispensed? done a b neither both intro

Explanation:

Step1: Calculate liquid dispensed in A

Initial volume is 9 mL, final is 5 mL. So volume dispensed in A is $9 - 5=4$ mL.

Step2: Calculate liquid dispensed in B

Initial volume is 9 mL, final is 4 mL. So volume dispensed in B is $9 - 4 = 5$ mL.

Answer:

A