Which of the following statements incorrectly describes a tool used by scientists? A. A compound light microscope enables a scientist to view objects too small for the unaided eye to see,
B. A beaker is a type of glassware a scientist uses in the lab to record data.

C. A scale is used to measure weight.
D. A ruler is used to measure length.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

the answer is c i believe

the answer for sodium is 0.186

the answer for rubidium is 0.251