true or false

( 3. 1. Chemical analysis method is usually used to determine micro-analyte in sample. ) 2. The spectrophotometry and chromatography belong to instrumental analysis. ) All of zero in experimental data is significant figure.( ) 2.236x1.1124 4. The result of =12.004471 has to be rounded to 12.00 by principle 1.036x0.2000 of rounding in calculation.( 5. The titrant must reacts with analyte in well-defined stoichiometric amount during titration ). 6. During standardization of KMnO4 with Na2C2O4, small amount of Mn+ can be added into the solution to accelerate reaction rate.( ) 7. The additional common ion always results in increasing of solubility of precipitate. ( ) 8. To determine the content of analyte (A) in Msample sample by titration with titrant (B), their stoichiometric reaction is aA +bB=cC+dD, then the concentration of A in bc, V. Mr weigh percent can be calculated by w -x100%. am sample 9. Sodium thiosulfate can be used as primary standard to prepare a standard solution directly. ( ) 10. When we want to determine the concentration of HCl by titration with NaOH standard solution, the NaOH standard solution should be standardized before use