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A laboratory has several chemists who work on one or more projects. Chemists also may use certain chemicals on each project. Attributes of CHEMIST include Employee ID (identifier), Name, and Phone No. Attributes of PROJECT include Project ID (identifier) and Start Date. Attributes of CHEMICAL include Compound No and Cost. The organization wishes to record Volume Used-that is, the amount of a given chemical used by a particular chemist working on a specified project. A chemist must be assigned to at least one project and one chemical on each project to which he or she is assigned. A given chemical need not be assigned to any project, and a given project need not be assigned to either a chemist or a chemical.