Atomic Number and Atomic Mass Number

Q. Which of the following is correct for sodium atom (Z = 11 and A = 23)?

1. 12 neutrons and 12 protons
2. 11 electrons and 12 protons
3. 11 electrons and 12 neutrons
4. 11 neutrons and 12 electrons

Q. What is the mass number of element X which has 8 electrons and 8 neutrons?

1. 16

Q.

What does the statement-"The atomic number of an atom of the same element never changes" mean?

Q. Which among the following is correctly represented?

1. ${}_{16}^8\text{O}$
2. ${}_{23}^{11}\text{Na}$
3. ${}_{10}^{19}\text{F}$
4. ${}_6^{12}\text{C}$

Q. An element Y is made up of 15 electrons and 16 neutrons. Which of the following is the correct symbolic representation of the element?

1. ${}_{15}^{31}Y$
2. ${}_{15}^{16}Y$
3. ${}_{31}^{15}Y$
4. ${}_{16}^{15}Y$

Q. The isotopes of Hydrogen H are ${}_{\text{1}}^{\text{1}}\text{H},{}_{\text{1}}^{\text{2}}\text{H}$ and ${}_{\text{1}}^{\text{3}}\text{H}$ respectively. What is the ratio of number of nucleons in these respective isotopes?

1. 1 : 1 : 1
2. 1 : 2 : 3
3. 2 : 1 : 3
4. 3 : 2 : 1

Q.

If an atom has two electrons in its outermost shell. Which among the following can be the atomic number of that atom?

1. 10

2. 11

3. 12

4. 13

Q.

The number of protons and electrons of an ion is 17 and 18. Find the name of the element symbol of the ion and the number of electrons gained/lost.

Q.

What are the three basic particles in atoms?

Q.

The atomic number of an atom is 19 and its mass number is 39. Which of the following are correct?

1. Number of electrons = 20

2. Number of neutrons = 19

3. Number of neutrons = 20

4. Number of protons = 19

Q. How many protons, neutrons and electrons are present in a carbon-12 atom?

1. 6 electrons, 6 protons, 6 neutrons
2. 6 electrons, 12 protons, 6 neutrons
3. 6 electrons, 6 protons, 12 neutrons
4. 6 electrons, 12 protons, 12 neutrons

Q. Which among the following is correctly represented?

1. ${}_6^{12}\text{C}$
2. ${}_{23}^{11}\text{Na}$
3. ${}_{10}^{19}\text{F}$
4. ${}_{16}^8\text{O}$

Q. Which of the following statements are correct about a neutral atom?

1. Atomic number = Number of protons = Number of electrons
2. Mass number = Number of protons + Number of neutrons
3. Atomic number = Number of protons + Number of electrons
4. Mass number = Number of neutrons = Number of electrons

Q. What is the mass number of aluminium if it has 13 protons and 14 neutrons?

1. 13
2. 14
3. 27
4. 28

Q. The number of electrons in a neutral atom with atomic number X and mass number Y is ________.

1. X - Y
2. Y - X
3. X + Y
4. X

Q.

The atom of an element X has 18 protons, 22 neutrons and 18 electrons. The atomic number of the element is _______.

1. 22
2. 36
3. 40
4. 18

Q. An atom of phosphorus has the symbol ${}_{15}^{31}\text{P}$. How many protons, electrons and neutrons are present in an atom of phosphorus?

1. Protons-15, electrons-15, neutron-16
2. Protons-15, electrons-16, neutrons-16
3. Protons-15, electrons-15, neutron-15
4. Protons-16, electrons-16, neutrons-15

Q. Deduce the number of neutrons from the atomic number (Z) and mass number (A). [3 marks]

Q. Which among the following is correctly represented?

1. ${}_6^{12}\text{C}$
2. ${}_{16}^8\text{O}$
3. ${}_{23}^{11}\text{Na}$
4. ${}_{10}^{19}\text{F}$