1. When an object is weighed on an analytical balance it is correct otosay that compared to the buoyancy of the balancing weights the buoyancy of the object
a. increases as the density of the object increases
b. decreases as the density of the inject increase
c.increases as the mass of the object increases
d.decreases as the mass of the mass of the object incrosses
e.is necessarily the smae as that of hte balancing weights
这道题是说称量的问题吗?
2.Which of the statements below about cabonate error is not true?
a.If methyl orange is ues as the indicator this type of error will be maximized.
b.It will be minimized if barium hydroxide is used as the titrant.
c. Sodium hydroxide can be prepared and then protected in such away as to avoid this type of error.
d. If the titrant is stored in a bottle equipped with atube containg Ascarite this error will be diminished.
e. A solution that has sodium carbonate at the bottom of its container has minimal error of this kind.
什么是cabonate error?
3.A student isolated 35.8g of AgCl from a photographic emulation. What is the maximum amount of sliver metal he could recover from this?
a.17.9g
b.26.9g
c.21.6g
d0.2g
e0.6g
貌似不是直接计算得到,是不是要考虑实际损耗?
4.A solution contains an unknown concentration of Ba2+ when 50ml of a 1M solution of Na2SO4 is added, BaSO4 just begins to precipitate. The final volume is 500ml. The solubility product of BaSO4 is 1*10-10. what is the original concentration of Ba2+?
a. 5*10-9 M
b. 2*10-9 M
c. 9*10-10 M
d.1.0*10-9 M
e. 1.1*10-9 M
通过计算可知至少为1.0*10-9 M,但是具体如何计算得到为e结果。