At the end of 40 hours, 6.25% of the original radionuclide is present in a sample. what is the half-life of the radionuclide?

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

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What relationship exists between an enzyme and a catalyst?