Saved Bookmarks
This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Mention the essential requirements for rusting of iron. |
| Answer» Essential requirements for rusting are the presence of oxygen / air and water. | |
| 2. |
How will you show that air is essential for burning ? |
| Answer» If you invert a glass tumbler over a burning candle, you will notice that the candle extinguishes after sometime . This is because the oxygen that supports burning is cut off when it is covered by the tumbler , and hence the candle stops burning. | |
| 3. |
Fuels react with oxygen to form ____________ and __________. |
|
Answer» Correct Answer - `CO_(2), H_(2)O` Fuels react with oxygen to form `underline( " carbon dioxide")and underline("water vapour.")` |
|
| 4. |
Fill in balanks. The products of combustion of fossil fuels are ___________ and __________. |
|
Answer» Correct Answer - carbon dioxide, water vapour The products of combustion of fossil fuels are `underline( " carbon dioxide")and underline("water vapour.")` |
|
| 5. |
Select the correct alternative from the given options . Gas X `to` Combustible and not a supporter of combustion Gas `to ` Combustible as well as a supporter of combustion . What could be X and Y ?A. X `to` Oxygen , Y `to ` NitrogenB. X `to` Carbon dioxide , Y `to` OxygenC. X `to` Oxygen , Y `to` Carbon dioxideD. X `to` Carbon dioxide , Y `to` Argon |
|
Answer» Correct Answer - b X is carbon dioxide and y is oxygen. |
|
| 6. |
What is the obervation when air comes in contact with a cool surface ? |
| Answer» The water vapour present in air gets condensed coming in contact with the cool surface . Hence , tiny droplets of water are oberved on the cool surface. | |
| 7. |
(a) Write the chemical name of the substance taken in the test tube. (b) What is the observation ? Give reasons. ( c) The air present in the test tube as shown in the diagram is sucked out . why ? |
|
Answer» (a) Lime water that is the solution of calcium hydroxide is taken in the test tube. (b) Lime water turn slighty turbid due to the carbon dioxide present in air. (c ) The air present in the test tube is sucked in order to create low pressure in the test tube. Due to low pressure , air rusher through the lime water. |
|
| 8. |
(a) Identify the mistakes (s) in the diagrams and give justification. What inference can be drawn from above diagrams ? |
|
Answer» (a) The level of water in test tube B should be higher . Water should occupy 1 /5 th of the total volume of test tube B. (b) since 1/5 th of the total volume of air is consumed due to the burning of phosphorous, this space gets occupied by water. |
|
| 9. |
Can an empty bottle be filled with water , when it is inverted into a basin of water vertically ? If not , what is the correct way of filling the bottle with water ? Justify your answer. |
| Answer» Since the bottle is filled with air , water cannot occupy this space unless a passage is provided for the expansion of air . Hence , the bottle should be inverted obliquenly. | |
| 10. |
When an empty spray pump is taken and air is blown on a clean mirror , the mirror remains clean. If we gently blow out air form lungus on the same mirror , the mirror misty . Give reason. |
| Answer» Exhaled air contains greater amount of water vapour than the normal air . When this air comes in contact with surface of the mirror , it condenses to form tiny water droplets and gives the appearance of mist . As a result , the mirror surface turns misty | |
| 11. |
Give reasons for the following. (a) Policemen regulating traffic often wear masks. (b) When water is heated , bubbles are observed. |
|
Answer» (a) Policemen wear masks in order to protect themselves from smoke and dust particles emitted by vehicles. (b) When water is heated , the air dissolved in it comes out in the form of tiny bubbles. |
|
| 12. |
Select the correct alternative from the given options . Who named the active component of air as oxygen?A. CavendishB. MayowC. LavoisierD. Priestley |
|
Answer» Correct Answer - c Lavoisiter named the active component of airas oxygen. |
|
| 13. |
Select the correct alternative from the given options. Which among the following is the source of `SO_(2)` ?A. Air conditionersB. Thermal power plantsC. Refrigeration systemsD. Dcgradation of organic wastcs |
|
Answer» Correct Answer - b Thermal power plants are the source of `SO_(2)`. |
|
| 14. |
Gas X is the major component of air . Among the following identify the true statement regarding X .A. X is used as a fire extinguisher.B. X is essential for rusting.C. X is highly soluble in water.D. X is a very unreactive gas. |
|
Answer» Correct Answer - d Gas X is nitrogen . X is very unreactive gas. |
|
| 15. |
Select the correct alternative from the given options . Which among the following compounds is used to identify the presence of water vapour in the atmosphere?A. Carbon dioxideB. PhosphorusC. Lime waterD. Anhydrous copper sulphate |
|
Answer» Correct Answer - d Anhydrous copper sulphate is used to identify the presence of water vapour in the atmosphere. |
|
| 16. |
Write some uses of air. |
|
Answer» (i) Used for respiration and combustion. (ii) Compressed air is used to fill tyres of vehicles. (iii) Blowing air is used to turn the blades of wind mills. Air helps in the movement of yachts, parachutes , gliders , ect. It also helps the birds , bats and insects to fly. |
|
| 17. |
Select the correct alternative from the given options . The evelope of air that surrounds the earth is calledA. AtmosphereB. LithosphereC. HydrosphereD. Exosphere |
|
Answer» Correct Answer - a The envelope of air that surround the earth is called atmosphere. |
|
| 18. |
The composition of air in terms of percentage of its varous components is given. (a) Identify X and Y. (b) Mention any two uses of X and Y . (c ) identify the gases present in Z. |
|
Answer» (a) X is nitrogen and Y is oxygen. (b) (i) Nitrogen dilutes the activity of oxygen. (ii) Nitrogen is essential for the growth of plants. (iii) Oxygen is essential for respiration. (iv) Oxygen support combustion. (c ) Z contains carbon dioxide , argon , helium , water vapour. |
|
| 19. |
Both the active component and the inactive component of play important roles . Illusrate. |
|
Answer» Active component is oxygen which is essential for respiration and combustion. Inactive component is nitrogen which dilutes the activity of oxygen and is essential for the growth of plants. |
|
| 20. |
Select the correct alternative from the given options . Identify the false statement among the following .A. Air occupies spaceB. Air has massC. Air can be compressedD. Air does not dissolve in water |
|
Answer» Correct Answer - d Air can dissolve in water . |
|
| 21. |
Name the products formed in the following. (a) Carbon + Oxygen `to` (b) Glucose + Oxygen `to` (c ) Phosphorus pentoxide + Water `to` |
|
Answer» (a) Carbon dioxide (b) Carbon dioxide and water vapour ( c) Phosphoric acid |
|
| 22. |
The volume of oxygen present in 750 l of air is ___________A. 172.5 lB. 187 .5 lC. 157 . 5 lD. 255.5 l |
|
Answer» Correct Answer - c Percentage by volume of oxygen present in 750 1 of air `=750xx21//100=157.51` |
|
| 23. |
It is not advisable to cook food on a wood fire in a closed room . Give reasons. |
| Answer» In a closed room , wood undergoes incomplete combustion to form carbon monoxide . Inhalation of CO reduces the oxygen carrying capacity of heamoglobin in the blood . Hence , excess inhalation of CO can be fatal. | |
| 24. |
Gas X is an active component of air . X reacts with caobon to form gas Y. Y is one of the products of _______________ and _____________.A. respiration , combustionB. photosynthesis , respirationC. combustion , transpirationD. photosynthesis, transpiration |
|
Answer» Correct Answer - a Gas X is oxygen and Y is carbon dioxide . Carbon dioxide is one of the products of both combustion and respiration. |
|
| 25. |
Thought air contains only about `0.03%` of carbon dioxide , it is a very important component of air. Give reasons. |
|
Answer» (i) Carbon dioxide is essential photosynthesis . In the presence of sunight green plants use carbon dioxide from air and water vapour from soil to make food by the process of photosynthesis. (ii) carbon dioxide extinguishes fire. (iii) Carbon dioxide is a gree house gas. |
|
| 26. |
Select the correct alternative from the given options. Identify the true statement among the following options.A. CO is a greenhouse gas.B. Global warming decreases the fertility of soil.C. Global warming causes melting of ice caps.D. Acid rain causes unseasonal rains. |
|
Answer» Correct Answer - c Global warming causes melting of ice caps. |
|
| 27. |
Select the correct alternative from the given options . Major component of CNG is _______A. ButaneB. MethaneC. EthaneD. Propane |
|
Answer» Correct Answer - b Major component of CNG is methane. |
|
| 28. |
Calculate the volume of oxygen and nitrogen present 250 l of air. |
|
Answer» Correct Answer - 195 l, 52.5 l Volume percentage of nitrogen in air is `78%rArr100l` of air contains 78 l of nitrogen 250 l of air contains `(78xx250)/(100)=195` l of nitrogen Volume percentage of oxygen in air is `21%` `rArr 100` l of air contains 21 l of oxygen 250 l of air contains `(250xx21)/(100)=52.5`l of oxygen. |
|
| 29. |
Name the component of air which extinguishes fire . Give reasons. |
| Answer» Carbon dioxide is used to extinguish fire `CO_(2)` is a non - supporter of combustion and non - combustible gas . Moreover , it is heavier than air and cuts off the contact between air and fire , and hence , it can be used to put off the fires. | |
| 30. |
The dust particles come into air from a number of sources . Give some examples for such sources. |
| Answer» Blowing of wind , traffic on the roads , dusting at home , earth moving operations construction activities and agricultural particles are the sources of dust particles. | |
| 31. |
Observe the figure given below and answer the following questions. (a) Will the observation be same in both the flask ? (b) What inference can be drawn from the given experiments? |
|
Answer» Lime water in both the flasks turns milky , but the extent of milkiness is more in flask B than that in A. Exhaled air contains more carbon dioxide than normal air. |
|
| 32. |
What conclustions can be draw based on the following diagrams ? |
|
Answer» (a) Air occupies space . (b) One fifth of air contains oxygen , oxygen supporst buring. (c ) Air contains water vapour. |
|
| 33. |
(a) Mention the substance used in white washing. (b) State the reason for using this substance for the above purpose. |
|
Answer» (a) The substance used for white washing is calcium hydroxide. (b) Carbon dioxide present in air reacts with calcium hydroxide to form a white insolubel solid mass of calcium carbonate. |
|