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What is the mass number of an atom that contains 39 protons, 51 neutrons, and 39 electrons? [massnumber] What is the symbol for the element?  [symbol]

After the age of 65, the recommended daily intake of calcium is 1500 mg. If a person takes in 1125 mg/day, what percent of the recommended daily intake is the person receiving?

How many protons, neutrons and electrons are there in a neutral atom of magnesium-25? [protons], [neutrons], [electrons] 

What is the mass number of an atom that contains 26 protons, 29 neutrons, and 26 electrons? [massnumber] What is the symbol for the element? [symbol]

You must use the factor-unit method to solve the following problem.  Show your work (conversion factors and units) by using the equation editor() in the toolbar.  Within the equation editor, use  for conversion factors.  Or, show your work (conversion factors and units) on a separate sheet of paper. Immediately after submitting your exam, upload a picture of your work into the Unit 1 Exam Pictures dropbox. Be sure to number your problems and circle your final answer.  A copy of your chemistry textbook is found to have a mass of 2.56×103 g.  What is this copy of your chemistry textbook is in kg? (1000 g = 1 kg)  

Classify the following as a physical or chemical property: The colorless gas hydrogen, reacts explosively when ignited in air.

What would you multiply moles of fluorine (F) by to get the units atoms of fluorine? 

The dense central core of the atom is called the ____.

Use whichever of the following equations necessary to convert 453 K to Fahrenheit.  (Use only these equations – decimal answers will not be accepted)  °C = 5/9 (°F – 32) °F = 9/5 (°C) + 32 °C = K – 273  

Which one of the following lists units of volume in increasing order (from smallest to largest)?