The 1000-ml graduated cylinder with marks every 100 ml has least count of 100 ml . It means it can not measure a volume less than 100 ml . It can also measure volume in the integral multiple of 100 ml like 200 ml , 300 ml , 400 ml etc perfectly . All these have significant figure of one .
It can not measure volume like 150 , 250 , 255 , 760 etc because these measurements are not the integral multiple of 100 . 750 is not a integral multiple of 100 so it can not measure volume of 750 ml.
it doesn't matter how many protons k has all the answers have electron with the positive charge when is negative the question is trying to distract you D is the only one that would use the electrons sign correctly
