Atomic Structure & Nuclear

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

• 100.0g
• 50.0g
• 12.5g
• 8.5g

Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?

• 0.25g
• 2.5g
• 25g
• 80g

The half-life of Zn-71 is 2.4 minutes. If 6.25 g of Zn-71 are needed for an experiment, how much is the orignal amount if it will take 9.6 minutes before the experiment can begin?

• 100.0g

• 50.0g

• 12.5g

• 8.5g

Barium-122 has a half-life of 2 minutes. If after 10 minutes a sample of 15.0 g is left, what mass must have been initially present?

• 30 g

• 480 g

• 240 g

• 120 g

After the third half-life, how much of the sample is left?

• 1/2
• 1/3
• 1/16
• 1/8

What is the atomic number?

• the number of protons in the nucleus

• the number of protons and neutrons in the nucleus

• the number of neutrons in the nucleus

• the number of protons in the energy levels

What is the mass number?

• the number of protons in the nucleus

• the number of protons and neutrons in the nucleus

• the number of neutrons in the nucleus

• the number of protons and electrons in the atom

What is the mass number of this atom?

• 1

• 3

• 4

• 7

Most of the mass in an atom is made up of _____________________?

• protons and electrons
• protons and neutrons
• neutrons and electrons
• electrons and quarks

In order for an atom to be neutral what has to be true?

• The atom has more protons than neutrons
• The atom has more neutrons than protons
• The atom has the same number of protons and neutrons
• The atom has the same number of protons and electrons