What element has 21 neutrons, 20 electrons and 20 protons

A car travels along a road at a steady speed of 60 mph. How far will it travel in 6 hours?

How does stability relate to how quickly a substance breaks down?

Which count of subatomic particles gives an atom its unique identity as an element, and represents its atomic number? a. the number of protons b. the number of neutrons c. the number of electrons d. the number of neutrons plus the number of protons

Assume that you measured exactly 2.0 mL of the sodium chloride solution into a small test tube. How many moles of sodium chloride are in the tube?

The series of processes that slowly change rocks from one kind to another is referred to as the

What is the pressure, in mm Hg, of 2.50 moles of an ideal gas if it has a volume of 50.0 liters when the temperature is 27.0° C?

What element has the same valence electrons as carbon A) N B) AI C) Si or D) Be

What element is represented by the following electron configuration: 1s22s22p63s23p64s23d4 Question 2 options: Cr Ca Ge Ar

He substance, cocl2, is useful as a humidity indicator because it changes from pale blue to pink as it gains water from moist air. What is its name?

The weighted average atomic mass of an element depends upon the a. relative abundance of protons in the element b. mass and relative abundance of each isotope of that element c. mass and relative abundance of each neutron of that element d.