Check the answers pls and don't ask to send one by one pls.... It just creates spam and is harder for both .....
Pls and fast

18. The relative error in the measurement of the side of a cube is 0.027. The relative error in the measurement of its volume is 
(1) 0.027
(2) 0.054
(3) 0.081
(4) 0.046
19. Zero error in an instrument introduces
(1) Systematic error
(2) Random error
(3) Least count error
(4) Personal error