Viraf J. Dalal solutions for New Simplified Middle School Chemistry [English] Class 7 chapter 7 - Air and Atmosphere [Latest edition]

State the meaning of the term Air

State the meaning of the term Atmosphere.

Name the important scientists and their studies which led to the discovery of the components of air.

Explain Lavoisier’s experiment which provided evidence to the discovery of components in air.

Tabulate the various components of air, including the components with variable composition.

Compare the three main components of air i.e. nitrogen, oxygen and carbon dioxide with reference to their density and solubility, nature and reactivity.

Of the total volume of air – 4/5th is nitrogen. State the utility or consequence of this ratio.

State how nitrogen is utilised by plants for their growth. Give a reason why nitrogen is used in flushing food packages.

Oxygen of the air is utilised for ‘combustiop’ and for ‘respiration’. Compare the two with a suitable examples.

State the utility of carbon dioxide for manufacture of food by plants.

State its role in warming the earth’s environment and in excess resulting in global warming.

State the utility of –
(a) Water vapour
(b) Rare or inert gases present in the air.

Give the environment effect of three polluting gases with a reason why nitrogen is not considered a polluting gas.

Describe simple experiments to show the presence of -

oxygen and nitrogen component in air using a bell jar

Describe simple experiments to show the presence of -

carbon dioxide in air using a test tube with outlets containing lime water.

Describe simple experiments to show the presence of -

water vapour in air using a glass tumbler and ice.

State four different properties of a compound and a mixture.

With reference to the stated properties give reasons why air is considered a mixture and not a compound.

Explain the term ‘air pollution’, with reference to air quality. State the sources of a few main pollutants.

Identify the acidic oxides responsible for acid rain. State how their presence results in formation of acid rain. Give a reason why acid rain damages heritage buildings.

In the laboratory preparation of oxygen from hydrogen peroxide answer the following:

Draw a neat labelled diagram for the method used in the above preparation.

In the laboratory preparation of oxygen from hydrogen peroxide answer the following:

Name the catalyst used in the preparation and state it’s function.

In the laboratory preparation of oxygen from hydrogen peroxide answer the following:

State the word equation for the reaction involving the above preparation of oxygen.

In the laboratory preparation of oxygen from hydrogen peroxide answer the following:

State the method of collection of the oxygen gas giving reasons.

Give word equation for the reaction of Non-metal:

Sulphur

Give word equation for the reaction of Non-metal:

carbon

Give word equation for the reaction of Non-metal:

phosphorus

Give word equation for the reaction of metal is:

sodium

Give word equation for the reaction of metal is:

calcium

Give word equation for the reaction of metal is:

magnesium with oxygen

Distinguish between:

Combustion and Respiration

Distinguish between:

Combustion & Rusting with suitable word equations only?

Give the main experimental points only to demonstrate that magnesium.

Give the main experimental points only to demonstrate that candle-gains weight on burning.

Give reasons for the following:

patients suffering from lung problems are kept in an oxygen tent.

Give reasons for the following:

oxygens finds utility in welding & cutting of metals.

Match the statements in List I with the correct answer from List II.

Give reason for the following:

Acid rain has caused damage to heritage structures such as the Taj Mahal.

Give reason for the following:

In the laboratory preparation of oxygen from potassium chlorate – manganese dioxide is added to the reactant.

Give reason for the following:

Oxygen gas does not affect moist blue litmus paper, but carbon dioxide turns it slightly pink.

Give reason for the following:

Oxidation of sulphur results in a product which turns moist blue litmus red.

Give reason for the following:

Combustion and respiration show similarity.

Name the following:

The product formed on oxidation of phosphorus.

Name the following:

The acid formed when the above product of oxidation of phosphorus, reacts with water.

Name the following:

The chemical name of rust.

Name the following:

The pollutant which combines with water vapour to give sulphuric acid – a product of acid rain.

Name the following:

The gas required for both combustion and rusting.

Fill in the blank:

Nitrogen of the air is utilized by plants for formation of _____.

Fill in the blank:

The gas evolved as a product of combustion as well as respiration is ______.

Fill in the blank:

A candle burns in a jar of oxygen, but gets extinguished in ______

Air has variable composition and hence there is ______ oxygen at lower altitudes than at higher altitudes.

Fill in the blank:

Rusting is a chemical reaction which involves _____ oxidation.

Draw a neat labelled diagram for the following experiment.

To determine the component of air used up in burning, by using phosphorus and a bell jar.

Draw a neat labelled diagram for the following experiment.

To study the presence of carbon dioxide in air.

Draw a neat labelled diagram for the following experiment.

To prove that oxygen is non-combustible, but supports combustion.

Draw a neat labelled diagram for the following experiment.

To prepare oxygen in the laboratory from hydrogen peroxide and a catalyst.

Draw a neat labelled diagram for the following experiment.

To demonstrate the burning of sulphur in a jar of oxygen.