The substances that are made up of the same kind of atom are called elements. For example, oxygen O 2 contains two oxygen atoms, It is a diatomic molecule of an element, and helium He is a monatomic molecule of an element. Zinc, copper and sodium, etc. are some metallic elements. Elements are arranged in a periodic table in the increasing order of their atomic number and categorised as metals, non-metals and metalloids.

EASY

Earn 100

What is an element?

Important Questions on Is Matter Pure?

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

The elements which behave like metals and non-metals are called _____. (transition metals / semi-metals)

MEDIUM

Science>Chemistry>Is Matter Pure?>Pure substances

Give two characteristics of a chemical compound.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

Benzene is a compound and it contains carbon and hydrogen.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

Element is the simplest form of matter.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

How will you purify a sample of impure sugar?

MEDIUM

Science>Chemistry>Is Matter Pure?>Pure substances

Define element, compound and mixture. What are homogeneous and heterogeneous mixtures? Give two differences between homogeneous and heterogeneous mixtures.

MEDIUM

Science>Chemistry>Is Matter Pure?>Pure substances

Distinguish between a compound and a mixture.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

The substances made up of only one type of atoms are called _____.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

Pick out the odd-one from the following:

Steam, diamond, silver, nitrogen.

HARD

Science>Chemistry>Is Matter Pure?>Pure substances

Hydrogen is the most abundant element in the earth’s crust.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

A pure substance which contains two different kinds of atoms is called _____.

HARD

Science>Chemistry>Is Matter Pure?>Pure substances

Two substances

X

and

Y

react to form a new substance

X_{2} Y

according to the following equation:

2 X + Y \to X_{2} Y

Which of the following are incorrect?
i. The product formed is an element.
ii. The product cannot be classified as a compound.
iii. The product will always have a fixed composition.
iv.

X_{2} Y

exhibits the properties of both A and B.

MEDIUM

Science>Chemistry>Is Matter Pure?>Pure substances

Explain the terms:

a.compound

b.colloid.

MEDIUM

Science>Chemistry>Is Matter Pure?>Pure substances

Give the names of the elements present in:
A. methane
B. glucose
C. bleaching powder
D. chalk
E. aqueous solution of calcium chloride
F. graphite
G. unleaded petrol.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

The composition of a _____ is fixed.

HARD

Science>Chemistry>Is Matter Pure?>Pure substances

Classify the following into elements, compounds and mixtures: water, seawater, dry ice, petrol, sugar, silver, brass, steel.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

What would you observe when a saturated solution of potassium chloride prepared at $60 ° C$ is allowed to cool to room temperature.

EASY

Science>Chemistry>Is Matter Pure?>Pure substances

_____ is a metal which is liquid at room temperature. (Bromine/ Mercury)