Someone who occupies a key role in the design, construction, and management of chemical operations to insure and improve the quality of life for people in and outside the plant is a(n)
chemical technician
information chemist
safety engineer
environmental chemist

environmental chemist

Explanation:

An environmnetal chemist is a professional who takes interest in the industrial activities and suggests preventive measures so as to produce least amount of wastes so that minimal or no loss of the environment outside the industry takes place. Such a professional will participate in all steps of chemical operations such as designing, construction and management.

a is the answer to this question

explanation:

"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"