Which of the following tests will completely identify anyone of surphur (VI) oxide, hydrogen, carbon (IV) oxide and nitrogen (II) oxide?
Pass each gas into water and test with blue litmus paper
Pass each gas into lime water
Expose each gas to atmospheric air
Pass each gas to concentrated tetraoxosulphate (IV) acid
Explanation
No explanation available
Video Explanation
No video available
Post your Contribution
Discussions (12)
Let's evaluate the options and find out which is the best;
* A. Pass each gas into water and test with blue litmus paper:
* This test helps us identify acids.
* Sulphur (VI) oxide (SO3) dissolves in water to form sulphuric acid, which will turn blue litmus paper red.
* Carbon (IV) oxide (CO2) dissolves in water to form a weak carbonic acid, which will also turn blue litmus paper slightly red.
* This test will not help to differentiate between hydrogen and Nitrogen (II) oxide.
* B. Pass each gas into lime water:
* Lime water is a solution of calcium hydroxide.
* Carbon (IV) oxide (CO2) will turn lime water milky due to the formation of calcium carbonate.
* The other gases will not have a visible reaction.
* C. Expose each gas to atmospheric air:
* Nitrogen (II) oxide (NO) will react with oxygen in the air to form brown nitrogen dioxide (NO2).
* Hydrogen will combust if there is a spark.
* Sulphur (VI) oxide and carbon (IV) oxide will not have a visible reaction.
* D. Pass each gas to concentrated tetraoxosulphate (IV) acid:
* This is concentrated sulphuric acid.
* This test is very dangerous, and should not be done without proper training and equipment.
* This test is not a good way to identify these gasses.
The best answer is C. Expose each gas to atmospheric air.
Here's why:
* Nitrogen (II) oxide (NO) will turn brown.
* Hydrogen (H2) will combust if there is a spark.
* Sulphur (VI) oxide (SO3) will fume in moist air.
* Carbon (IV) oxide (CO2) will have no visible reaction.
By observing these reactions, you can completely identify each gas.
myschool is definitely correct
WHY?
Well because
To test for SO2 pass the gas into acidified potassium heptaoxodichromate (vi) solution (K2Cr2O7) or pass into acudified potassium tetraoxomanganate (iv) KMnO4 and for the result iy decolourizes the solution eithout leaving a yrllow ppt
to test for H2
it gives a pop sound when a splint(wooden) is brought at tge tip of the test tube
to test for CO2
turns lime water milky when passed through lime water indicaying presence of CaCO3
hope thus helps
option c is d right answer make research before saying or opposing the answers pls
A. Water + litmus isn't super specific 
- SO₃ + H₂O → H₂SO₄ (acid, turns litmus red)
- CO₂ + H₂O → H₂CO₃ (weak acid, maybe pink)
- H₂, NO kinda neutral → not distinct
C. Air exposure doesn't ID them uniquely 
- NO oxidizes to NO₂ (brown), others not super obvious
Lime water (B) is more distinct 
*A* — passing each gas into water and testing with blue litmus paper.
Here’s why it works and the others don’t:
*What happens with option A*
Gas In water Blue litmus result
**Sulphur(VI) oxide** SO₃ SO₃ + H₂O → H₂SO₄ Strong acid → turns blue litmus **red immediately & strongly**
**Carbon(IV) oxide** CO₂ CO₂ + H₂O → H₂CO₃ Weak acid → turns blue litmus **red faintly/slowly**
**Hydrogen** H₂ Doesn’t dissolve/react **No change**, stays blue. Test with lighted splint → pops
**Nitrogen(II) oxide** NO Very slightly soluble, neutral **No change**, stays blue. Expose to air → turns brown NO₂
So A gives you 3 distinct outcomes right away: strong acid, weak acid, neutral.
Then H₂ vs NO can be split because H₂ pops with a lighted splint, while NO gives brown fumes in air.
*Why the others fail*
*B: Lime water*
Only CO₂ gives a white ppt of CaCO₃. SO₃, H₂, and NO give no visible change, so you can’t tell those 3 apart.
*C: Expose to air*
Only NO shows a change — colorless NO → brown NO₂. The other 3 stay the same, so useless for full ID.
*D: Conc. H₂SO₄*
SO₃ dissolves in it, but CO₂, H₂, NO do nothing visible. Can’t distinguish the last 3.
So *A is the only test that gives enough info to completely identify all four* if you add simple follow-up tests for the two neutral gases.
Hopefully this helps 🙂
D is the Right Option
conc H2SO4 is a strong oxidizing agent and all of them can be Oxidized except CO2.
