An element has atomic number 10 and an atomic mass of 20. how many neutrons are in the atom of this element? a. 10 b. 20 c. 30 d. 0 e. 200

Answer : The correct option is, (A) 10

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.  That means,

Atomic number = number of protons = number of electrons

Atomic mass : It is defined as the sum of number of protons and number of neutrons.

Atomic mass = Number of neutrons + Number of protons

As we are given that,

The atomic number of an element = 10

The atomic mass of an element = 20

Now we have to determine the number of neutrons.

Atomic number = number of protons = 10

Atomic mass = Number of neutrons + Number of protons

Number of neutrons = Atomic mass - Number of protons

Number of neutrons = 20 - 10 = 10

Therefore, the number of neutrons are, 10

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6