Question

A. Choose the correct option.
1.
The nucleus of an atom contains
a. electrons and neutrons.
b. protons and neutrons.
d. only protons.
c. protons and electrons.
2. Electrons are denoted by
a. e.
b. e.
c c. en
d. et
3. The electronic configuration of an element with atomic number 19 is
a. 2,8,9,
b. 2, 8, 8, 1.
c. 2, 7, 10.
d. 2, 8, 7, 2.
4.
Mass number is the sum of the number of
a. electrons and protons.
b. electrons and neutrons.
c. protons and neutrons.
d. neutrons, electrons and protons.​

Answer 1

Answer:

1)- protons and neutrons

2)- e- or e

3)- 4s1

4)- protons and neutrons