We are given the number '0.0020' and we are to indicate the number of significant figures in the given measured number.
According to the rules of significant figures, numbers that are non-zero, zeros between any two significant numbers and the ending zeros in the decimal position are categorized as significant figures.
Since there is one non-zero number and one ending zero in the decimal position, therefore 0.0020 has 2 significant figures.
If you are given the
standard potential for the reduction of X^2+ is +0.51 V, and the standard
potential for the reduction of A^2+ is -0.33, just add the two. The standard
potential for an electrochemical cell with the cell is 0.18V
