Atomic Mass and Mass Number

Q.

An atom has a mass number 35 and the atomic number 17. The number of neutrons in its nucleus are ________.

Q.

In the diagram given below, structure of atom is depicted, where we are able to see orbits and electrons. How many neutrons and protons are present in the nucleus?

1. 20 protons and 20 neutrons

2. 19 protons and 20 neutrons

3. 19 neutrons and 20 protons

4. 20 electrons and 19 protons

Q. Match the elements with its respective atomic numbers:

1. 1
2. 11
3. 3
4. 8

Q.

From the symbol ${}_{16}{}^{32}\mathrm{S}$ give :

(b) Mass number of sulphur.

Q.

What do you understand by the term ‘mass number’?

Q.

From the symbol ${}_{40}{}^{20}\mathrm{Ca}$ state:

Mass number of Ca

Q. State the relation between the number of protons, the number of neutrons and the atomic mass number (A) of an element.

Q.

What is atomic number ?

Q.

Three different atoms of hydrogen are represented as ${}_1{}^1\mathrm{H};{}_1{}^2\mathrm{H};{}_1{}^3\mathrm{H}$. What do the subscripts and superscripts represent?

Q.

The ion of an element has 3 units positive charge. The mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

1. 13

2. 10

3. 14

4. 16

Q.

Complete the following:

Carbon contains _______ protons and ________ neutrons.

Q. Match the following elements with their respective atomic numbers.

1. 3
2. 8
3. 11
4. 1

Q. The number of neutrons present in the element ${}_Z^A\text{X}$ is given by ________.

1. $\text{A-Z}$
2. $\text{Z}$
3. $\text{Z + A}$
4. $\text{Z - A}$

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. The atomic number of an element is equal to the number of protons present in an atom.

1. True
2. False

Q. If ${}_{12}^{25}A$ and ${}_{18}^{40}B$ are two elements, which of the following are correct about them?

1. Mass number of B is 40
2. Mass number of A is 12
3. Atomic number of B is 18
4. Mass number of A is 25

Q. An atom of an element X contains eight protons, eight neutrons and eight electrons. Therefore, the atomic number of the element X is eight.

1. False
2. True

Q. Which of the following defines the mass number of an atom?

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

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

Q. Statement 1: Two different elements can have same number of protons.
Statement 2: The atomic number is the number of protons in an atom.

1. Both statements are true.
2. Both statements are false.
3. Only statement 1 is true.
4. Only statement 2 is true.