An atom has an atomic number of 15 and a mass number of 31. How many protons are there in the atom?

• 15
• 31
• 16
• 47

Tags

NGSS.MS-PS1-1

Calcium has three different isotopes. One has a mass of 35.00 amu; another has a mass of 41.00 amu; and another has a mass of 40.00 amu. Which isotope is the most abundant of the three?

• 40.00 amu
• 41.00 amu
• 35.00 amu
• impossible to tell

4.35% of all X atoms have a mass of 39.946 amu. 83.79% have a mass of 41.941 amu, 9.50% have a mass of 42.941 amu, and 2.36% have a mass of 43.939 amu. What is the average atomic mass of atom X?

• 41.97 amu
• 42.19 amu
• 10.43 amu
• 40.04 amu

Tags

NGSS.MS-PS1-1

Compute the average atomic mass for silicon:

• 27.977
• 28.09
• 28.976
• The average mass cannot be determined from provided information.

Tags

NGSS.MS-PS1-1

Which of the following elements is an alkali metal?

• calcium

• magnesium

• mercury

• sodium

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

How was Mendeleev's periodic table arranged?

• by increasing atomic mass

• by decreasing atomic mass

• by increasing atomic number

• by decreasing atomic number

Tags

NGSS.HS-PS1-2

The three main groups of elements are metals, nonmetals, and

• inert gases.

• alkali metals.

• radioactive isotopes.

• semiconductors/metalloids.

Tags

NGSS.HS-PS1-1

Elements in an elemental family have similar

• atomic symbols.

• atomic sizes.

• atomic weights.

• chemical properties.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which group is very stable due to the fact that they have a full outermost energy level?

• alkali metals

• halogens

• alkaline-earth metals

• noble gases

Tags

NGSS.HS-PS1-1

Which of the following is a property of group 18 elements?

• malleable

• brittleness

• high electrical conductivity

• unlikely to react with other elements

Tags

NGSS.HS-PS1-1