Olympiad Test: Physical And Chemical Changes - 1


20 Questions MCQ Test Science Olympiad Class 7 | Olympiad Test: Physical And Chemical Changes - 1


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Attempt Olympiad Test: Physical And Chemical Changes - 1 | 20 questions in 40 minutes | Mock test for Class 7 preparation | Free important questions MCQ to study Science Olympiad Class 7 for Class 7 Exam | Download free PDF with solutions
QUESTION: 1

Burning of wood is a ______ change.

Solution:
QUESTION: 2

Neutralization change is a

Solution:
QUESTION: 3

What is the main cause of acid rain?

Solution:

Acid rain occurs mainly because of carbon dioxide, sulphur dioxide and nitrogen dioxide which are all pollutants. 

QUESTION: 4

Some pieces of chalk were taken and mixed with water. In this change, how many new substances are formed?

Solution:

This is a physical change even though the characteristics of this mixture is different from the original substances can retain their properties and can be get back easily. 

QUESTION: 5

Two changes are stated below
(i) a piece of magnesium gives out bright flames when burnt.
(ii) a piece of iron glows red when heated strongly.

Q. Which of these is a chemical change?

Solution:
QUESTION: 6

Which of the following changes is not a chemical change?

Solution:
QUESTION: 7

Which of the following Venn diagrams shows the relationship between changes correctly?

Solution:

All chemical changes are irreversible and the original substances can not be obtained. 

QUESTION: 8

Which one is a physical change?

Solution:
QUESTION: 9

When iron pieces are added to a blue colour copper sulphate solution, the colour of copper sulphate changes to

Solution:

When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

QUESTION: 10

The gas released when vinegar is mixed with baking soda is

Solution:
QUESTION: 11

Which of the following is not a physical change?

Solution:

No new substances are formed in all these changes. 

QUESTION: 12

Manisha took a little bit of soil from her garden and mixed it with water. When she dipped blue litmus in it, the litmus turned red. By adding which of following to her garden will she get better plant growth?

Solution:

The soil is acidic and should be neutralized by adding slaked lime (calcium hydroxide) which is a base. 

QUESTION: 13

Three substances given below are kept in the open for a few days and some changes were observed.

Which of th e substances will show chemical changes?

Solution:
QUESTION: 14

Pooja took a candle in a vessel and heated the vessel. Even though the candle did not burn, it changed its shape and state. What kind of change is this?

Solution:

The candle started melting, but since no new substance was formed it is a physical change. 

QUESTION: 15

The product formed when Mg is burnt in air is:

Solution:
QUESTION: 16

Rusting takes place in

Solution:
QUESTION: 17

Which of the following is an antacid?

Solution:

Magnesium hydroxide or Mg(OH)2 is an antacid. It is also known as milk of magnesia. It neutralizes excess HCl (acid) present in stomach  

QUESTION: 18

Adding sodium chloride to water is a

Three different substances were taken and tested with litmus paper. The results are given below. Based on the results answer the questions 19 to 24.

Solution:
QUESTION: 19

What could be the substance X?

Solution:
QUESTION: 20

What could be the substance Y?

Solution:
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