Elements and Compounds

Q.

Why are there 18 electrons in the third shell?

Q.

If an atom ‘A’ has atomic number 19 & mass number 39, state-

i) its electronic configuration

Q. An element ‘X’ has a mass number 19 and contains 10 neutrons. What is the valency of ‘X’?

1. 1
2. 3
3. 5
4. 7

Q.

An atom of an element is represented as ${}_{11}{}^{23}\mathrm{X}$

1. What does the numeral 23 indicate?
2. What does the numeral 11 indicate?
3. What is the number of protons in X?
4. What is the number of electrons in X?
5. How are the electrons distributed around the nucleus of X?
6. What is the number of neutrons in X?

Q.

Explain the Distribution of Electrons in different shells of following atoms

1. Lithium
2. Nitrogen
3. Neon
4. Magnesium
5. Silicon

Q.

Write the electronic configuration of the following element:

${}_{19}{}^{39}\mathrm{K}$

Q.

Write the electronic configuration of the following of the following element:

${}_6{}^{12}\mathrm{C}$

Q.

Define shells.

Q.

The K shell of an atom has a maximum of ___ electrons (8/2).

Q. A) What are isotopes? Give two examples of isotopes of elements.

[2 Marks]

B) Give any three applications of isotopes.

[3 Marks]
[TSSCERT]

Q.

Which energy shell is closer to the nucleus of an atom?

Q. An atom Q has a total number of 17 electrons. Calculate the number of electrons in the N-shell.

Q.

The formula used to represent the maximum number of electrons present in a shell

1. 2n²

2. n²

3. 2n

4. n

Q.

An element X has mass number 4 and atomic number 2. Find the valency of X

Q. The amount of heat energy required to change 1 kg of solid into liquid at its melting point is known as_________.

1. latent heat of fusion
2. latent heat of vaporisation
3. latent heat of sublimation
4. latent heat of condensation

Q. An atom of an element has three electrons in the M shell. If M is the outermost shell, what is the atomic number of that element?

1. 3
2. 10
3. 13
4. 8

Q. Which amongst the following gases can be classified as compound?

1. Hydrogen chloride
2. Oxygen
3. Nitrogen
4. Chlorine

Q. A neutral atom of an element has a nucleus with a nuclear charge 11 times and mass 23 times as that of a hydrogen nucleus. What is the ratio of electrons to protons in its stable positively charged ion?​

1. 23 : 11
2. 10 : 11
3. 20 : 21
4. 10 : 12

Q. An atom of an element has three electrons in the M shell. If M is the outermost shell, what is the atomic number of that element?

1. 3
2. 10
3. 13
4. 8

Q. According to Dalton's atomic theory, matter is made up of indivisible particles called atoms.

1. True
2. False