In the following table the mass number and the atomic number of certain elements are given: Element A B C D E Mass number 1 7 14 40 40 Atomic number 1 3 7 18 20 (A) State the pair of isobars from the above table. (B) What would be the valency of the element C listed in the above table? (C) Which two subatomic particles are equal in number in a neutral atom?

(A) Atoms of different elements having the same mass number but different atomic number is called as isobar. In given table, element D and E is having same mass number and different atomic number. Hence, D and E are isobars. (B) The element C in given table have atomic number 7 . So, electronic configuration of element C is 1 s 2 2 s 2 2 p 3 . Hence, number of electrons in valence shell is 3 and valency of element C is 3 . (C) Proton and electron are the two subatomic particles that are equal in number in a neutral atom.

E M B I B E

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 7

MEDIUM

9th CBSE

IMPORTANT

Earn 100

A student heats a beaker containing ice and water. He measures the temperature of the content of the beaker as a function of time. Which of the following figures would correctly represent the result? Justify your choice.

Important Questions on Sample Paper

MEDIUM

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 8

In the following table the mass number and the atomic number of certain elements are given:

Element	A	B	C	D	E
Mass number	$1$	$7$	$14$	$40$	$40$
Atomic number	$1$	$3$	$7$	$18$	$20$

(A) State the pair of isobars from the above table.

(B) What would be the valency of the element C listed in the above table?

(C) Which two subatomic particles are equal in number in a neutral atom?

EASY

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 9

In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called the law of conservation of _____.

EASY

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 9

A group of atoms carrying a fixed charge on them is called _____.

MEDIUM

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 9

The formula unit mass of

{Ca}_{3} ({PO}_{4})_{2}

is _____.

MEDIUM

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 10

The following substances are added to water kept in a beaker:

(i) Sugar (ii) Milk (iii) Sand

Observe the mixtures created for stability (setting down of particles) and filterability.

MEDIUM

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 4>Q 11

How will you prepare (i) a mixture and (ii) a compound, using iron filings and sulphur. Can you just by seeing, judge that the mixture formed is a homogeneous and heterogeneous mixture?

MEDIUM

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 5>Q 1

Although sponge is a solid, yet we can compress it. Why?

EASY

9th CBSE

IMPORTANT

Essentials of Chemistry>Chapter 9 - Sample Paper>Sample Paper 5>Q 2

J. Chadwick discovered a subatomic particle which has no charge but has a mass equal to a proton. Name the particle and give its location in an atom.