Share & grow the world's knowledge!
We want to connect the people who have knowledge to the people who need it, to bring together people with different perspectives so they can understand each other better, and to empower everyone to share their knowledge.
Observe the following diagram showing the conditions under which a metal ‘M’ corrodes. List your observations in each of the three cases A, B and C with the reason, if the metal ‘M’ is generally protected against corrosion by the method of galvanisation.
Case A: Significant corrosion will be observed on the metal surface because the protective zinc coating on the metal readily react with oxygen and the moisture present in the moist air. Case B: No corrosion will be observed due to the oil layer with reacts with acts as a barrier and effectively inhiRead more
Case A: Significant corrosion will be observed on the metal surface because the protective zinc coating on the metal readily react with oxygen and the moisture present in the moist air.
Case B: No corrosion will be observed due to the oil layer with reacts with acts as a barrier and effectively inhibiting corrosion.
Case C: Minimal to no corrosion will be observed due to lack of moisture in the presence of dry air.
See lessA person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a glass prism in its path in such a manner that the beam falls on the face AB of the prism as shown in the figure. A screen S is placed on the other side of the prism, facing AC. On turning the prism slowly, a beautiful band of colours is obtained on the screen. It is the spectrum of sunlight. (a) Name the phenomenon due to which a prism splits the incident white light into a band of colours. (b) State the reason of getting a band of seven colours in the above case.
(a) The phenomenon is called dispersion of light. (b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours. (c) To show recombination of spectrum ofRead more
(a) The phenomenon is called dispersion of light.
(b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours.
(c) To show recombination of spectrum of white light, Newton used two prisms. The first prism disperses white light into seven colours. When this spectrum is passed through a second, inverted prism, it recombines the seven colours back into white light.
Labelled Ray Diagram:
See lessRakvi performed an activity by taking ethanoic acid and sodium hydrogen carbonate as shown in the diagram given below. The diagram shows an experimental setup where ethanol is oxidised to ethanoic acid using an oxidizing agent, producing CO2 gas sodium bicarbonate (NaHCO3) may be used to test the acidic nature of the product. Answer the following questions based on the given information: (i) What is the observable change when CO2 gas reacts with lime water in the in this experiment? (ii) Rakvi observed that a salt X is formed with the evolution of gas Y. Identify the salt X and evolved gas Y. (iii) Write the chemical equation of the reaction involved.
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of caRead more
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of carbon dioxide gas.
(b) When ethanoic acid reacts with sodium hydrogen carbonate, the products formed are sodium ethanoate (X), water, and carbon dioxide gas (Y). The reaction demonstrates the typical acid–carbonate reaction, producing effervescence due to carbon dioxide release. The sodium salt formed is soluble, while the gas evolved can turn lime water milky.
(c) Carbon dioxide released from the reaction is confirmed using lime water. It reacts with calcium hydroxide to form insoluble calcium carbonate, which makes the solution appear milky. The balanced reaction is:
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. This simple test is widely used to detect carbon dioxide gas.
See lessStudy the figure given below and answer the following questions: (A) Name the process depicted in the diagram. (B) Write the composition of gases collected at anode and the cathode. (C) Write the balanced chemical equation of the reaction taking place in this case. (D) The reaction does not take place if a few drops of dilute sulphuric acid are not added to water. Why?
ANSWER: (A) Electrolytic decomposition of water/electrolysis of water. (B) The gas collected at cathode is hydrogen which is double the volume of oxygen collected at anode. (C) 2H2O (l) + Electric current → 2H2 (g) + O2 (g) When an electric current is passed through water, it undergoes electrolysis.Read more
ANSWER:
(A) Electrolytic decomposition of water/electrolysis of water.
(B) The gas collected at cathode is hydrogen which is double the volume of oxygen collected at anode.
(C) 2H2O (l) + Electric current → 2H2 (g) + O2 (g) When an electric current is passed through water, it undergoes electrolysis. Two molecules of liquid water (2H₂O) decompose to form hydrogen gas (2H₂) and oxygen gas (O₂). Hydrogen collects at the cathode, while oxygen collects at the anode.
(D) Water is not a good conductor of electricity sulphuric acid is added in the water to make, it a good conductor of electricity.
See lessZinc granules on treating with an acid X, form zinc sulphate (ZnSO₄) salt along with the evolution of a gas Y, which burns with a pop sound when brought near to a burning candle. Identify acid X and gas evolved Y:
ANSWER: [C] Explanation: When an acid reacts with a metal, hydrogen gas is liberated. In the given reaction, when dilute sulphuric acid reacts with zinc granules, hydrogen gas is liberated and zinc sulphate solution is formed: Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂ (g) The presence of hydrogen gas is teRead more
ANSWER: [C]
Explanation: When an acid reacts with a metal, hydrogen gas is liberated. In the given reaction, when dilute sulphuric acid reacts with zinc granules, hydrogen gas is liberated and zinc sulphate solution is formed:
Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂ (g)
The presence of hydrogen gas is tested by bringing a lighted candle near it. When a lighted candle is brought near the test tube containing hydrogen gas, it burns with a “pop sound” making a little explosion. Hence, acid “X” is sulphuric acid and gas “Y” is hydrogen gas.
See less