Question

3 what is the mass of an atom with 5 protons, 7 neutrons, and 5 electrons? 17 5 10 12 7 4 from the below picture, how many valence electrons are present? 5 3 7 2

Explanation:

Step1: Recall mass - number formula

The mass number (A) of an atom is the sum of the number of protons (p) and neutrons (n). The formula is $A=p + n$.

Step2: Identify values of p and n

Given that the number of protons $p = 5$ and the number of neutrons $n=7$.

Step3: Calculate the mass number

Substitute the values into the formula: $A=5 + 7=12$.

Since the second question "From the below picture, how many valence electrons are present?" does not have the picture provided, we can only answer the first - question.

Answer:

12 (corresponding to the fourth option in the first question)