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Question 1 Report
Wrought iron is obtained by heating cast iron in a furnace with?
Answer Details
Wrought iron is a type of iron that is very malleable and ductile, meaning it can be easily shaped and formed into various objects. It is obtained by heating cast iron in a furnace with haematite, also known as iron(III) oxide. When cast iron is heated with haematite in a furnace, a chemical reaction takes place where the haematite reacts with the carbon in the cast iron to produce carbon dioxide gas. This reaction also produces molten iron, which is then further heated to remove any impurities like sulfur and phosphorus. This molten iron is then poured into molds to form ingots of wrought iron. Therefore, haematite is essential in the process of obtaining wrought iron from cast iron.
Question 2 Report
There is a large temperature interval between the melting point and the boiling point of metal because:
Answer Details
The correct answer is: "melting does not break the metallic bond but boiling does." The metallic bond is the force of attraction between metal atoms, which holds them together to form a solid. When a metal is heated, its temperature increases, and at a certain point, the energy provided by the heat is enough to overcome the metallic bond and cause the metal to melt. However, even in the liquid state, the metallic bond remains intact, which is why metals have a very high melting point. On the other hand, when the temperature is further increased, the energy provided by the heat becomes enough to break the metallic bond, and the metal atoms become completely detached from one another. This results in the metal boiling and turning into a gas. Because the metallic bond is much stronger than other types of intermolecular forces, such as van der Waals forces, it requires a lot of energy to break, resulting in a large temperature interval between the melting point and boiling point of metal.
Question 3 Report
Which of the following increases as boiling water changes to steam?
Answer Details
The degree of disorder of the system increases as boiling water changes to steam. When water is boiled and changes to steam, the water molecules gain energy and become more disordered, which means that the molecules move more rapidly and the entropy of the system increases. The temperature of the system also increases during this process, but the degree of disorder is the factor that specifically increases as the water changes to steam. The number of molecules and activation energy remain constant during this phase transition.
Question 4 Report
6g of Mg was to 100cm3 of 1 moldm3 H2 SO4 . What mass of Mg remained undissolved? (Mg = 24)
Answer Details
The balanced chemical equation for the reaction between magnesium (Mg) and sulfuric acid (H2SO4) is: Mg + H2SO4 -> MgSO4 + H2 According to the equation, one mole of Mg reacts with one mole of H2SO4 to produce one mole of magnesium sulfate (MgSO4) and one mole of hydrogen gas (H2). Since the concentration of the sulfuric acid is 1 moldm3, this means that there is one mole of H2SO4 in every 1 liter (1000 cm3) of solution. To determine the amount of Mg that reacts with the H2SO4, we need to use stoichiometry. One mole of Mg reacts with one mole of H2SO4, so the amount of Mg that reacts with 1 moldm3 of H2SO4 is given by: 6g / 24g/mol = 0.25 mol Since the reaction is 1:1, this means that 0.25 mol of H2SO4 is consumed in the reaction. The volume of the solution is 100cm3 (0.1 dm3), so the amount of H2SO4 in the solution is: 1 mol/dm3 x 0.1 dm3 = 0.1 mol The amount of H2SO4 that remains after the reaction is: 0.1 mol - 0.25 mol = -0.15 mol This negative value means that all of the H2SO4 was consumed in the reaction, and there is excess Mg left over. The mass of Mg that remains undissolved is given by: 0.15 mol x 24g/mol = 3.6g Therefore, the correct answer is 3.6g.
Question 5 Report
Which of the following substances is not a homogeneous mixture?
Answer Details
The substance that is not a homogeneous mixture is flood water. Flood water is typically a mixture of various substances, such as sediment, dirt, debris, and organic matter, that have been carried along by the water. As such, flood water is usually a heterogeneous mixture, meaning that it does not have a uniform composition throughout. In contrast, filtered sea water, soft drinks, and writing ink are all examples of homogeneous mixtures, where the components are evenly distributed and the mixture has a uniform composition throughout.
Question 7 Report
In the extraction of iron, hot air is introduced into the blast furnace through?
Answer Details
In the extraction of iron, hot air is introduced into the blast furnace through tuyeres. Tuyeres are nozzles that are located at the bottom of the blast furnace, and they are used to blow hot air into the furnace. The hot air helps to burn the coke (a fuel made from coal) which provides the heat needed to melt the iron ore. The air also helps to remove the waste gases that are produced during the reaction, allowing the iron to be extracted more efficiently.
Question 8 Report
Ethene, when passed into concentrated H2SO4, is rapidly absorbed. The product is diluted with water and then warmed to produce
Answer Details
When ethene is passed into concentrated H2SO4, it undergoes electrophilic addition reaction to form ethyl hydrogen sulfate as the product. The reaction mixture is then diluted with water and warmed to produce ethanol as the main product. Therefore, the answer is ethanol.
Question 9 Report
Calcium forms complexes with ammonia because
Answer Details
The reason why calcium forms complexes with ammonia is that it has empty d-orbitals.
Question 10 Report
An organic compound decolourized acidified KMnO4 solution but failed to react with ammonical AgNO3 solution. The organic compound is likely?
Answer Details
The given information suggests that the organic compound is an unsaturated compound (because it decolorized the acidified KMnO4 solution), but it does not contain a functional group that reacts with ammonical AgNO3 solution. Therefore, the likely organic compound is an alkene or an alkyne. Carboxylic acids can also react with acidified KMnO4 solution, but they would also react with ammonical AgNO3 solution to form a silver carboxylate salt. Alkanes are saturated compounds and do not react with either reagent, so they would not decolorize the acidified KMnO4 solution. Therefore, based on the given information, the most likely option is either an alkene or an alkyne.
Question 11 Report
How many neutrons are present in atom with mass number and atomic number 37 and 17 respectively?
Answer Details
The atomic number of an atom represents the number of protons in the nucleus of the atom. Since the atomic number given is 17, it means that there are 17 protons in the nucleus. The mass number of an atom represents the total number of protons and neutrons present in the nucleus. Therefore, if the mass number is given as 37, it means that the total number of protons and neutrons in the nucleus is 37. To determine the number of neutrons in the nucleus, we can subtract the atomic number (which represents the number of protons) from the mass number (which represents the total number of protons and neutrons). Thus, the number of neutrons in the atom with a mass number of 37 and an atomic number of 17 is: Number of neutrons = Mass number - Atomic number = 37 - 17 = 20 Therefore, the answer is 20.
Question 12 Report
A certain liquid has a high boiling point. It is viscous, non-toxic, and miscible with water to be hygroscopic; this liquid most likely to be
Answer Details
The liquid is most likely to be option number 4: CH3OHCHOH2OH, which is also known as glycerol or glycerin. Glycerol has a high boiling point of 290°C, which is much higher than the boiling points of the other options. It is also a viscous liquid, which means it is thick and sticky. Glycerol is non-toxic, and it is often used in food, pharmaceuticals, and cosmetics. Furthermore, glycerol is miscible with water, which means that it can be easily mixed with water to form a homogeneous solution. It is also hygroscopic, which means that it can absorb water from the air. These properties make glycerol a useful substance in many applications, such as as a moisturizer in skincare products or as a humectant in food processing.
Question 13 Report
Which of the following roles does sodium chloride play in preparation? It
Answer Details
The role that sodium chloride (NaCl) plays in soap preparation is to separate soap from glycerol. When fats or oils are hydrolyzed with an alkali, such as sodium hydroxide (NaOH), the result is a mixture of soap and glycerol. Adding NaCl to this mixture helps to induce the precipitation of the soap, allowing it to be separated from the glycerol. This process is known as "salting out" and is used to purify the soap and remove impurities. Sodium chloride does not react with glycerol or accelerate the decomposition of fat and oil. Also, it does not convert the fatty acid to its sodium salt as this conversion is done by the alkali (such as NaOH) during the saponification process.
Question 14 Report
An organic compound contains 69% carbon, 15.3% hydrogen and 30.7% oxygen. Calculate the the empirical formula [C=12, H = 1, O = 16]
Answer Details
Question 15 Report
Hard water is water with high concentrations of dissolved ions, in particular calcium and
Answer Details
Hard water is water that contains high amounts of dissolved minerals, specifically calcium and magnesium ions. These minerals come from the rocks and soil that the water flows through and can accumulate in the water as it travels to your home. When you use hard water, it can leave mineral deposits on your pipes, fixtures, and appliances, which can reduce their efficiency and lifespan. It can also make soap less effective and leave your skin feeling dry and itchy. Therefore, it is important to treat hard water if it is a problem in your area.
Question 16 Report
A chemical widely used as a fertilizer is?
Answer Details
The chemical widely used as a fertilizer is nitrochalk. Nitrochalk is a type of fertilizer that contains a mixture of ammonium nitrate and calcium carbonate. Ammonium nitrate provides the necessary nitrogen for plant growth, while calcium carbonate helps to balance the soil's pH level. This combination of nutrients helps to promote healthy plant growth and increase crop yields. Nitrochalk is commonly used in agriculture and gardening to fertilize crops such as corn, wheat, and soybeans, as well as fruits and vegetables.
Question 18 Report
An organic compound with fishy smell is likely to have a general formula?
Answer Details
The organic compound with a fishy smell is most likely to have the general formula RNH2, which represents a primary amine. Amines are organic compounds that contain a nitrogen atom bonded to one or more carbon atoms. Primary amines have one alkyl or aryl group and two hydrogen atoms bonded to the nitrogen atom. Some primary amines have a fishy smell, which is caused by the presence of volatile amines. These amines are small molecules that can easily evaporate and have a strong odor, similar to that of fish. Examples of compounds that have a fishy smell include trimethylamine, which is found in fish, and butylamine, which is used in the production of rubber and pharmaceuticals. In summary, the organic compound with a fishy smell is likely to have the general formula RNH2, which represents a primary amine.
Question 19 Report
The oxidation number of oxygen in BaO2 is
Answer Details
To determine the oxidation number of oxygen in BaO2, we can use the fact that the overall charge of a compound must be zero. Barium (Ba) is a Group 2 element and has an oxidation state of +2. The compound BaO2 has no net charge, so the sum of the oxidation states of all the atoms must be zero. Let x be the oxidation state of oxygen in BaO2. Therefore, we have: (+2) + 2(x) = 0 Solving for x, we get: x = -1 Therefore, the oxidation number of oxygen in BaO2 is -1.
Question 20 Report
Alkanes are used mainly?
Question 21 Report
| GAS | CO2 | N2 | O2 |
| % BY VOLUME | 4 | 72 | 24 |
The above table shows the compositions of the atmosphere of planet X. Which of these gases are present in higher percentages on earth?
Answer Details
Question 22 Report
A sample of gas with an initial volume of 2.5 dm3 is heated and then allowed to expand to 7.5 dm3 at constant at pressure. What is the ratio of the final temperature of the initial absolute temperature?
Answer Details
According to Charles's Law, the ratio of the initial and final temperatures is equal to the ratio of the initial and final volumes at constant pressure. The ratio of the final volume to the initial volume is: Vf / Vi = 7.5 dm3 / 2.5 dm3 = 3 Therefore, the ratio of the final temperature to the initial temperature is also 3: Tf / Ti = Vf / Vi = 3 So the answer is 3:1.
Question 24 Report
Which of the following will precipitate in dil. HCl
Answer Details
Among the given options, only CuS will precipitate in dilute HCl. CuS is insoluble in dilute HCl, and hence it will precipitate when added to dilute HCl. However, the other options will dissolve in dilute HCl, and hence they will not precipitate. ZnS will dissolve in dilute HCl to form ZnCl2 and H2S. Na2S will react with dilute HCl to produce H2S and NaCl. FeS will dissolve in dilute HCl to form FeCl2 and H2S. Therefore, the correct answer is (4) CuS.
Question 25 Report
An organic functional group which can likely decolorize ammoniacal silver nitrate is?
Answer Details
The organic functional group that can likely decolorize ammoniacal silver nitrate is an alkyne. When ammoniacal silver nitrate is added to a solution containing an alkyne functional group, a white or yellowish precipitate of silver acetylide is formed. Silver acetylide is a highly explosive compound and is sparingly soluble in water, causing it to appear as a white or yellowish solid precipitate. This reaction is used as a test to detect the presence of an alkyne functional group in an organic compound. In contrast, alkanes, alkenes, and alkanols do not react with ammoniacal silver nitrate, so they cannot decolorize it. Therefore, an organic functional group that can likely decolorize ammoniacal silver nitrate is an alkyne.
Question 26 Report
A quantity of air passed through a weighted amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of
Answer Details
When air is passed through alkaline pyrogallol, the oxygen in the air is absorbed by the pyrogallol, resulting in an increase in the weight of the pyrogallol. The other gases in air, namely nitrogen, neon, and argon, do not react with pyrogallol under these conditions. Therefore, the answer is oxygen.
Question 27 Report
The boiling point of water, ethanol, toulene and butan-2-ol are 373.0k, 351.3k, 383.6k and 372.5k respectively, which liquid has the highest vapour pressure at 323.0k
Question 28 Report
What is the shape of a molecule of CCl4?
Answer Details
The shape of a molecule of CCl4 is tetrahedral.
Question 29 Report
Which of the following constitutes a mixture? I. Petroleum II. Rubber latex III. Vulcanizer’s solution IV. Carbon (iv) sulphide
Answer Details
Question 30 Report
The sub-atomic particles located in the nucleus of an atom are?
Answer Details
The sub-atomic particles located in the nucleus of an atom are neutron and proton. The nucleus is the dense core of an atom that contains most of its mass. Protons are positively charged particles found in the nucleus, and they determine the atomic number of the element. Neutrons are neutral particles found in the nucleus, and they help stabilize the nucleus by balancing the repulsive forces between the positively charged protons. Electrons, on the other hand, are negatively charged particles that are located outside the nucleus in energy levels or shells. They are attracted to the positively charged nucleus by electrostatic forces and are involved in chemical bonding between atoms. The number of protons in the nucleus determines the identity of the element, while the number of neutrons determines its isotopes. Isotopes of an element have the same number of protons but different numbers of neutrons in the nucleus. In summary, the two sub-atomic particles located in the nucleus of an atom are neutron and proton.
Question 31 Report
A certain volume of gas at 298k is heated such that its volume and pressure are now four times the original values. What is the new temperature?
Answer Details
We can use the ideal gas law to solve this problem, which states that PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature in kelvin. If the volume and pressure are both increased by a factor of 4, then the new volume V' and new pressure P' are given by: V' = 4V P' = 4P Substituting these values into the ideal gas law, we get: (4P)(4V) = nR(T') Simplifying this equation, we get: 16PV = nRT' Dividing both sides by PV, we get: 16 = nRT' / PV Since n, R, and P are constant, we can simplify this to: 16 = T' / T Solving for T', we get: T' = 16T Therefore, the new temperature is 16 times the original temperature. Substituting T = 298 K, we get: T' = 16 x 298 K = 4768 K So the correct answer is 4768.0K.
Question 32 Report
The pollutant usually presents in a city which generates its electricity from coal?
Answer Details
The pollutant that is usually present in a city that generates its electricity from coal is sulfur dioxide (SO2), also known as sulfur(iv)oxide. When coal is burned to generate electricity, sulfur compounds in the coal are released into the air as SO2. This gas can react with other pollutants and atmospheric conditions to form smog, which can be harmful to human health and the environment. Therefore, it is important to reduce the use of coal in electricity generation and promote cleaner and more sustainable energy sources to reduce the levels of SO2 and other harmful pollutants in the air.
Question 33 Report
Complete dehydrogenation of ethyne yields
Question 34 Report
30 cm3 of oxygen at 10 atmosphere pressure is placed in a 20 dm3 container. Calculate the new pressure if the temperature is kept constant.
Answer Details
Given:
First, convert all volumes to the same units. Since 1 dm3dm3 is 1000 cm3cm3:
𝑉2=20 dm3=20×1000 cm3=20000 cm3V2=20dm3=20×1000cm3=20000cm3
Now, using Boyle's Law:
𝑃1𝑉1=𝑃2𝑉2P1V1=P2V2
Substitute the known values into the equation:
10×30=𝑃2×2000010×30=P2×20000
300=𝑃2×20000300=P2×20000
Solve for 𝑃2P2:
𝑃2=30020000P2=20000300
𝑃2=0.015 atmospheresP2=0.015atmospheres
Therefore, the new pressure if the temperature is kept constant is:
Question 35 Report
Answer Details
The addition of charcoal to the filter bed of sand during water treatment for township supply is to remove odors and improve the taste of the water. Charcoal is a porous material that can adsorb impurities and chemicals from the water, such as dissolved organic matter that can contribute to unpleasant tastes and odors. This process helps to produce a better-quality drinking water that is free from unpleasant tastes and odors. It should be noted that while the addition of charcoal can help remove impurities, it does not kill germs or prevent tooth decay or goiter. Other water treatment methods, such as disinfection with chlorine or ultraviolet light, are required to kill harmful microorganisms and ensure the safety of the drinking water.
Question 36 Report
Zn + 2HCL → ZnCl2 + H2
What happens to zinc in the above reaction?
Answer Details
In the above reaction, zinc (Zn) reacts with hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2). The chemical equation for the reaction is: Zn + 2HCl → ZnCl2 + H2 During the reaction, zinc atoms lose two electrons each and get oxidized to form positively charged zinc ions (Zn2+), as they react with the hydrogen ions (H+) from the hydrochloric acid to form zinc chloride. The hydrogen ions, on the other hand, gain an electron each and get reduced to form hydrogen gas molecules (H2). Therefore, in the given reaction, zinc is getting oxidized, as it loses electrons and forms a positively charged ion. Hence, the correct option is "oxidized."
Question 37 Report
2-methylprop-1-ene is a structural isomer of?
Question 38 Report
The sulphide that is commonly used in coating electric fluorescent tubes is?
Answer Details
The sulphide commonly used in coating electric fluorescent tubes is Zinc Sulphide. Zinc Sulphide is a type of material that glows when it is exposed to ultraviolet light. When ultraviolet light is generated inside a fluorescent tube, it excites the Zinc Sulphide particles, causing them to emit visible light. This visible light is what we see as the bright light coming from the tube. So, Zinc Sulphide acts as a phosphor and helps in producing the bright light in fluorescent tubes.
Question 39 Report
SO2 + O2 → 2SO3
In the reaction above, the most suitable catalyst is?
Answer Details
The most suitable catalyst for the given reaction is vanadium(V)oxide (V2O5). Vanadium(V)oxide is a commonly used catalyst for the oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3). The reaction is an exothermic reaction, and it occurs at high temperatures (around 450-500°C) in the presence of a catalyst. V2O5 is an effective catalyst for this reaction because it has a high surface area and can provide active sites for the reaction to occur. The vanadium ions in the V2O5 catalyst undergo redox reactions with the sulfur dioxide and oxygen molecules, which promotes the formation of sulfur trioxide. Chromium(VI)oxide and iron(III)oxide are not suitable catalysts for this reaction because they are not effective at promoting the oxidation of sulfur dioxide to sulfur trioxide. Copper(I)oxide can be used as a catalyst for the reaction, but it is not as effective as vanadium(V)oxide.
Question 40 Report
If the volume of a given mass of a gas at 0ºc is 29.5cm3 . What will be the volume of the gas at 15ºc, given that the pressure remains constant.
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