1.
An atom has 2 electrons, 2 neutrons and 2 protons. What is the atomic number of this atom?
Correct Answer
C. 2
Explanation
The atomic number of an atom is equal to the number of protons in its nucleus. In this case, the atom has 2 protons, so the atomic number is 2.
2.
An atom of which element has 11 electrons?
Correct Answer
B. Sodium
Explanation
Sodium has 11 electrons because it is located in group 1 of the periodic table, which means it has 1 valence electron. In addition to the valence electron, sodium also has 2 electrons in the first energy level and 8 electrons in the second energy level, totaling 11 electrons. Potassium, magnesium, and neon do not have 11 electrons, so they are not the correct answer.
3.
How many electrons are in the first shell of a carbon atom?
Correct Answer
B. 2
Explanation
The first shell of an atom can hold a maximum of 2 electrons. Since carbon has an atomic number of 6, it has 6 electrons in total. Therefore, the first shell of a carbon atom contains 2 electrons.
4.
How many electrons are in the outer shell of a nitride 3- ion?
Correct Answer
C. 8
Explanation
The nitride ion has a charge of 3-, which means it has gained three electrons. Nitrogen, the element in the nitride ion, has five electrons in its outer shell. When it gains three electrons, it fills up its outer shell and now has a total of eight electrons in its outer shell. Therefore, the correct answer is 8.
5.
Which element has 2 electrons, 2 neutrons and 2 protons?
Correct Answer
C. Helium
Explanation
Helium is the correct answer because it has 2 electrons, 2 neutrons, and 2 protons. It is the second lightest element in the periodic table and belongs to the noble gas group. Helium is a colorless and odorless gas that is commonly used in balloons and as a coolant in various applications. Its atomic number is 2, indicating that it has 2 protons in its nucleus, which determines its identity as an element. The 2 electrons and 2 neutrons complete the atomic structure of helium.
6.
How many electrons are in the first shell of a hydrogen atom?
Correct Answer
A. 1
Explanation
The first shell of a hydrogen atom can hold a maximum of 2 electrons. However, since hydrogen only has 1 electron, there is only 1 electron present in the first shell.
7.
An atom has 7 electrons - 2 in its inner shell and 5 in its outer shell. What group of the periodic table is this element found in?
Correct Answer
D. 5
Explanation
The element with 7 electrons - 2 in the inner shell and 5 in the outer shell belongs to group 5 of the periodic table. Group 5 elements have 5 electrons in their outermost shell and exhibit similar chemical properties due to the same number of valence electrons.
8.
A fluorine atom has 9 electrons - 7 in its outer shell and 2 in its inner shell. How many electrons would be in the outer shell if it were to become a fluoride ion?
Correct Answer
D. 8
Explanation
When a fluorine atom becomes a fluoride ion, it gains one electron. This electron fills up the outer shell, which can hold a maximum of 8 electrons. Therefore, the fluoride ion would have 8 electrons in its outer shell.
9.
An atom contains 9 electrons. How many neutrons are there in the nucleus of this atom?
Correct Answer
A. 10
Explanation
An atom contains a nucleus at its center, which is made up of protons and neutrons. The number of protons determines the atomic number of an element, while the sum of protons and neutrons gives the atomic mass. In this case, the atom contains 9 electrons, so the atomic number is 9. The atomic mass is not given, so we cannot determine the exact number of neutrons. However, since the atomic mass is likely to be close to 19, the closest option is 10 neutrons.
10.
An element has 2 electrons in its inner shell, 8 in its next shell and 1 in its outer shell. What type of ion would it form?
Correct Answer
B. 1+
Explanation
The element has 2 electrons in its inner shell, 8 in its next shell, and 1 in its outer shell. Since the outer shell is not complete, it will tend to lose 1 electron to achieve stability. By losing 1 electron, the element will have a net positive charge of 1+, forming a cation. Therefore, the correct answer is 1+.
11.
A fluorine atom has 9 electrons - 7 in its outer shell and 2 in its inner shell. How many electrons would be in the outer shell if it were to become a fluoride ion?
Correct Answer
D. 8
Explanation
When a fluorine atom gains an electron to become a fluoride ion, it achieves a stable electron configuration similar to that of a noble gas, in this case, neon. The outer shell of neon contains 8 electrons, so when fluorine gains an electron, it will have 8 electrons in its outer shell, making the correct answer 8.