JOM TRY 1

An atom has 15 protons and 16 neutrons. What is the appropriate atomic symbol for this element?

• 
• 
• 
• 

For the above isotopic notation, which are the correct value of proton, neutron and electron respectively.

• Protons: 31, Neutrons: 41, Electrons: 28

• Protons: 31, Neutrons: 41, Electrons: 34

• Protons: 28, Neutrons: 41, Electrons: 31

• Protons: 31, Neutrons: 41, Electrons: 31

Both of these species have similar ...

• atomic number

• mass number

• number of electrons

• number of neutrons

Select a CORRECT statement for element R with 35 protons and 80 neutrons.

• Element R has an atomic number of 80 and a mass number of 35.

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• Element R has 45 electrons if it has a charge of 2−.

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An element has two naturally occurring isotopes: ¹⁰B (abundance = 19.9%, mass = 10.01 amu) and ¹¹B (abundance = 80.1%, mass = 11.01 amu). Calculate the average atomic mass of this element.

• 10.11 amu

• 10.81 amu

• 10.91 amu

• 11.11 amu

Based on the mass spectrum given, which statement is INCORRECT?

• Zr has 5 isotopes

• Zirconium-91 is the least abundant isotope

• Zirconium-90 is the most abundant isotope

• The relative atomic mass of Zr is 91.32

"A chemical formula that gives the total number of atoms of each element in each molecule of a substance."

The statement above best describe ...

• Empirical formula

• Molecular formula

• Molecular mass

• Structural formula

Which of the following NOT an empirical formula?

• CH

• C₅H₁₀

• CaCl₂

• Na₂O

Which of the following statement best describe empirical formula?

• The simplest structure of a molecule

• The simplest ratio of atoms of each element in a molecule

• The simplest number of mole of a molecule

• The simplest concentration of a molecule

Percentage by mass can be defined as ...

• percentage of the mass of solute per mass of solution

• percentage of the mass of solute per mass of solute

• percentage of the mass of solvent per mass of solution

• percentage of the mass of solvent per mass of solute