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CHEMISTRY [1 Mark Question Answer]

Air · ICSE STD 7 (ICSE - English Medium). 9 questions.

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[1 Mark Question Answer]

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9 questions · timed · auto-graded

Question 11 Mark
What is the use of liquid nitrogen in hospitals ?
Answer
Liquid nitrogen is used in hospitals for storing and preserving blood, tissues, etc as it provides a very low temperature.
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Question 21 Mark
What are the chemicals used in a soda-acid fire extinguisher ?
Answer
Sodium bicarbonate solution and dilute sulphuric acid.
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Question 31 Mark
State the use of manganese dioxide in the laboratory preparation of oxygen from hydrogen peroxide.
Answer
Manganese dioxide is used as a catalyst in the laboratory preparation of oxygen from hydrogen peroxide.
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Question 51 Mark
What happenes when magnesium reacts with oxygen ?
Answer
Magnesium reacts with oxygen to undergo oxidation and forms magnesium oxide
$\underset{\text {magnesium}}{2Mg} + \underset{\text {oxygen}}{O_2} \longrightarrow \underset{\text {Magnesium oxide}}{2MgO}$
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Question 61 Mark
What type of oxidation occurs in the burning of phosphorus ?
Answer
Spontaneous oxidation
$\underset{\text {phosphorous}}{P_4} + \underset{\text {oxygen}}{5O_2} = \underset{\text {phosphorous pentoxide}}{P_4O_{10}}$
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Question 81 Mark
Which gas is produced on heating sodium nitrate ?
Answer
$\underset{\text {sodium nitrate}}{2Nano_3} \xrightarrow{heat}\underset{\text {sodium nitrate}}{2Nano_2}+\underset{\text {oxygen}}{ O_2\uparrow}$
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Question 91 Mark
How did Priestley prepare oxygen ?
Answer
Priestley by prepared oxygen by heating mercury (II) oxide using the infra red rays of the sun.
$\begin{array}{c}2 HgO \\ \text { mercury (II) oxide }\end{array} \xrightarrow{\text { heat }} \underset{\text { mercury }}{2 Hg }+\underset{\text { oxygen }}{ O _2}$
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