Loading....
|
Press & Hold to Drag Around |
|||
|
Click Here to Close |
|||
Question 1 Report
Answer Details
Carbon dioxide (CO2) has a linear molecular geometry, with two oxygen atoms bonded to the central carbon atom. Each bond between carbon and oxygen is a double bond, consisting of two pairs of electrons shared between the atoms. Therefore, there are two bonding pairs in each of the carbon-oxygen double bonds, giving a total of four bonding pairs in CO2. The answer is 4.
Question 2 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 3 Report
What is the shape of a molecule of CCl4?
Answer Details
The shape of a molecule of CCl4 is tetrahedral.
Question 4 Report
H2SO4 is used to remove rust on the surface of iron (picking) before electroplating. The type of reaction involved is
Answer Details
The type of reaction involved when using H2SO4 to remove rust on the surface of iron is a redox reaction. This is because the sulfuric acid oxidizes the iron in the rust, converting it into iron(II) sulfate, while the acid itself is reduced to sulfur dioxide. The overall reaction can be written as follows: Fe2O3(s) + 3H2SO4(aq) → Fe2(SO4)3(aq) + 3H2O(l) In this reaction, the iron in Fe2O3 is oxidized from a +3 to a +2 oxidation state, while the sulfur in H2SO4 is reduced from a +6 to a +4 oxidation state. This transfer of electrons between the reactants is what defines a redox reaction.
Question 5 Report
2H2 + O2 → 2H2 O
From the equation above, calculate the volume of unreacted oxygen gas if a mixture of 50cm3 of hydroden and 75cm3 of oxygen are involved
Answer Details
The balanced chemical equation shows that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water vapor. Therefore, the stoichiometric ratio of hydrogen to oxygen is 2:1. In this problem, there are 50cm3 of hydrogen gas and 75cm3 of oxygen gas. Since the gases are at the same temperature and pressure, their volumes are directly proportional to the number of moles of gas present. Using the stoichiometric ratio, we can calculate that the amount of oxygen gas required to react completely with 50cm3 of hydrogen gas is (1/2) * 50cm3 = 25cm3. Since there are 75cm3 of oxygen gas present, there must be (75cm3 - 25cm3) = 50cm3 of unreacted oxygen gas remaining. Therefore, the volume of unreacted oxygen gas is 50cm3. Answer: 50cm3
Question 6 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 7 Report
An organic compound which decolorizes bromine water is likely to be?
Answer Details
Question 8 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 9 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.
Question 10 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 11 Report
Electrons enter into orbitals in order of increasing energy as exemplified by?
Answer Details
Question 12 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 13 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 14 Report
Which of the following will act as both oxidizing agents and reducing agents?
Answer Details
The oxidizing and reducing properties of a substance depend on its ability to gain or lose electrons. A substance that can gain electrons acts as an oxidizing agent, while a substance that can lose electrons acts as a reducing agent. Among the given options, both Cl2 (chlorine gas) and SO2 (sulfur dioxide) can act as both oxidizing and reducing agents depending on the reaction conditions. - Cl2 can act as an oxidizing agent when it gains electrons to form Cl- ions, and it can act as a reducing agent when it loses electrons to form Cl+ ions. For example, in the reaction Cl2 + 2KBr → 2KCl + Br2, chlorine gas is acting as an oxidizing agent since it is gaining electrons from bromide ions to form bromine gas. However, in the reaction 2Cl- + Cl2 → 2Cl2-, chlorine gas is acting as a reducing agent since it is losing electrons to form chloride ions. - SO2 can act as an oxidizing agent when it gains electrons to form sulfite ions (SO32-), and it can act as a reducing agent when it loses electrons to form sulfur trioxide (SO3). For example, in the reaction SO2 + 2H2S → 3S + 2H2O, sulfur dioxide is acting as a reducing agent since it is losing electrons to form elemental sulfur. However, in the reaction 2SO32- + O2 → 2SO42-, sulfur dioxide is acting as an oxidizing agent since it is gaining electrons to form sulfate ions. H2S (hydrogen sulfide) and NH3 (ammonia) are not likely to act as both oxidizing and reducing agents under normal conditions. H2S tends to act as a reducing agent by donating electrons to oxidizing agents, while NH3 tends to act as a reducing agent by donating electrons to oxidizing agents or as a base by accepting protons.
Question 15 Report
The IUPAC name for CICH2-CH2-CH2-OH is
Answer Details
The IUPAC name for CICH2-CH2-CH2-OH is 3-chloropropan-1-ol. To name the compound using the IUPAC nomenclature system, we start by identifying the longest continuous chain of carbon atoms that contains the functional group (-OH). In this case, the longest chain contains three carbon atoms, so the root name is propane. Next, we identify the position of the substituent (-Cl) on the chain. The substituent is attached to the third carbon atom in the chain, so the name of the compound becomes 3-chloropropane. Finally, we add the suffix -ol to indicate that the compound contains an alcohol functional group (-OH), so the complete name of the compound is 3-chloropropan-1-ol. Therefore, the correct answer is 3-chloropropan-1-ol.
Question 16 Report
Which of the following is stable to heat
Answer Details
Out of the given options, K2CO3 is stable to heat.
Question 17 Report
When marble is heated to 1473K, another whiter solid is obtained which reacts vigoriously with water to give an alkaline solution. The solution contains
Answer Details
The white solid obtained when marble (calcium carbonate, CaCO3) is heated to 1473K is calcium oxide (CaO), also known as quicklime. When quicklime reacts vigorously with water, it forms calcium hydroxide (Ca(OH)2), which is an alkaline solution. Therefore, the solution obtained from the reaction of quicklime with water contains calcium hydroxide (Ca(OH)2).
Question 18 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 19 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 20 Report
One of the active components of baking powder is
Answer Details
The active component of baking powder is sodium bicarbonate (NaHCO3). It is responsible for the leavening or rising of baked goods by releasing carbon dioxide gas when it reacts with an acid. Other ingredients in baking powder, such as monocalcium phosphate and sodium aluminum sulfate, provide the acid component for the reaction to occur. Magnesium sulfate (MgSO4) and calcium sulfate (CaSO4) are not typically used in baking powder, and sodium chloride (NaCl) is simply table salt and not an active ingredient in leavening.
Question 21 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 22 Report
2-methylprop-1-ene is a structural isomer of?
Question 23 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 24 Report
On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell
Answer Details
The electrochemical series is a list of metals and ions arranged in order of their decreasing tendency to lose or gain electrons, and thus, their ability to act as reducing or oxidizing agents. The higher the position of a metal or ion in the electrochemical series, the greater its tendency to lose electrons and undergo oxidation, while the lower its position, the greater its tendency to gain electrons and undergo reduction. In an electrolytic cell, the cathode is the electrode where reduction occurs, meaning that cations (positively charged ions) are attracted and gain electrons to form neutral atoms or molecules. Based on the electrochemical series, the ion with the higher position in the series will have a greater tendency to gain electrons and be discharged at the cathode, while the ion with the lower position will have a lower tendency and may not be discharged at all. Among the given options, the electrochemical series order is: Cu2+ > Sn2+ > Fe2+ > Zn2+ Therefore, Cu2+ has the highest tendency to be discharged at the cathode and undergo reduction, while Zn2+ has the lowest tendency. So, in an electrolytic cell, Cu2+ will be discharged at the cathode, while Zn2+ may not be discharged at all, depending on the conditions of the cell.
Question 25 Report
A metal which can be used as sacrificial anode for preventing corrosion of length of iron pipe is
Answer Details
Question 26 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 27 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 28 Report
Which of the following is used as a moderator to control nuclear fission?
Answer Details
Heavy water (D2O) is used as a moderator to control nuclear fission. A moderator is a substance that is used to slow down the neutrons produced in a nuclear reaction, making them more likely to be captured by the fuel nuclei and causing further fission. Heavy water is a type of water that contains a larger amount of the isotope deuterium (D) than regular water. Deuterium has an extra neutron compared to the more common hydrogen isotope, and this makes heavy water more effective at slowing down neutrons than regular water. Lead, iron, and chromium are not typically used as moderators in nuclear reactors. Lead can be used as a shield to absorb radiation, while iron and chromium are used in the construction of the reactor vessel and other components.
Question 29 Report
which of these compounds exhibits resonance
Answer Details
The compound that exhibits resonance is benzene.
Question 30 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 31 Report
A piece of radioactive element has initially 8.0×10^22 atoms. The half life of two days after 16 days the number of atom is
Question 32 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 34 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 35 Report
Copper (II) tetraoxosulphate (IV) is widely used as
Answer Details
Copper (II) tetraoxosulphate (IV), also known as copper sulfate or CuSO4, is widely used as a fungicide and a disinfectant. As a fungicide, copper sulfate is effective in controlling fungal diseases in plants, including mildew, leaf spots, and blights. It is also used as a fungicide in swimming pools to prevent the growth of algae. As a disinfectant, copper sulfate is effective in killing bacteria and viruses. It is used in a variety of applications, including in the production of animal feed, as a preservative for wood, and in water treatment to kill bacteria and algae. While copper sulfate has been used as a fertilizer in the past, its use in this capacity has largely been replaced by other compounds. It is not commonly used as a purifier.
Question 36 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 37 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 38 Report
Which of the following compound is NOT the correct formed compound when the parent metal is heated in air?
Answer Details
The compound that is NOT correctly formed when the parent metal is heated in air is: tri-iron tetraoxide (Fe2O). This is because the correct compound formed from the heating of iron in air is iron (III) oxide or Fe2O3. The formula for tri-iron tetraoxide is incorrect, as it implies that there are only three iron atoms in the compound when there should be four.
Question 39 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 40 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.
Would you like to proceed with this action?