Question

same length is measured by metre rod Vernier caliper and screw gauge which one has less uncertainty​

Answer 1

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Whichever one you happen to have. But, assuming you have all 3, I take you mean meter rod to be a ruler marked with lines and a screw gage to be a hole where you can check screw sizes. Simply passing an object through a hole to “measure" really isn't a measure as a screw gage is limited in the sizes it has. A caliper is pretty accurate within the size range it is capable of but larger than that it is terrible.

Answer 2

$\huge{ \underline{\underline{ \fcolorbox{white}{black}{\sf{answer : - }}}}}$Whichever one you happen to have. But, assuming you have all 3, I take you mean meter rod to be a ruler marked with lines and a screw gage to be a hole where you can check screw sizes. Simply passing an object through a hole to “measure" really isn't a measure as a screw gage is limited in the sizes it has. A caliper is pretty accurate within the size range it is capable of but larger than that it is terrible.