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Ajụjụ 1 Ripọtì
Chlorine is a common bleaching agent. This is not true with
Akọwa Nkọwa
Chlorine is not a common bleaching agent for wet litmus paper, wet pawpaw leaf, and most wet fabric dyes. It is commonly used as a bleaching agent for printer's ink.
Ajụjụ 2 Ripọtì
The IUPAC nomenclature of the structure is
Akọwa Nkọwa
The IUPAC nomenclature of the structure is "2-chloro-2-methylbutane". The name is derived by first identifying the longest carbon chain, which in this case contains four carbon atoms (butane). The carbon chain is numbered from one end to the other, giving the substituents the lowest possible numbers. Starting from either end, we can see that the first carbon atom has a chlorine atom attached to it, which is represented by the prefix "chloro-". Moving along the chain, the second carbon atom has a methyl group attached to it, which is represented by the prefix "methyl-". Since the substituents are in the second position from each other, we use the prefix "di-" to indicate two substituents in this position. Finally, we use the suffix "-ane" to indicate that the molecule is an alkane. Therefore, the correct name for this molecule is "2-chloro-2-methylbutane".
Ajụjụ 3 Ripọtì
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?
Akọwa Nkọwa
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.
Ajụjụ 4 Ripọtì
which of these compounds exhibits resonance
Akọwa Nkọwa
The compound that exhibits resonance is benzene.
Ajụjụ 5 Ripọtì
Electrons enter into orbitals in order of increasing energy as exemplified by?
Ajụjụ 6 Ripọtì
6g of Mg was to 100cm3 of 1 moldm3 H2 SO4 . What mass of Mg remained undissolved? (Mg = 24)
Akọwa Nkọwa
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.
Ajụjụ 7 Ripọtì
One of the active components of baking powder is
Akọwa Nkọwa
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.
Ajụjụ 8 Ripọtì
Which of the following substances is not a homogeneous mixture?
Akọwa Nkọwa
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.
Ajụjụ 9 Ripọtì
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
Akọwa Nkọwa
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
Ajụjụ 10 Ripọtì
Zn + 2HCL → ZnCl2 + H2
What happens to zinc in the above reaction?
Akọwa Nkọwa
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."
Ajụjụ 11 Ripọtì
Wrought iron is obtained by heating cast iron in a furnace with?
Akọwa Nkọwa
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.
Ajụjụ 12 Ripọtì
In the preparation of salts, the method employed will depend on the?
Akọwa Nkọwa
The method employed in the preparation of salts will depend on the composition of the salt. Different salts have different chemical properties, and the method used to prepare them will depend on these properties. For example, some salts can be easily dissolved in water, while others are not very soluble and may require the use of a different solvent or special conditions to dissolve. The dissociating ability, stability to heat, and precipitating ability of the salt may also play a role in determining the preparation method, but the most important factor is the composition of the salt.
Ajụjụ 13 Ripọtì
The reactions below represent neutralization reaction, in which of them is the value of ΔH highest?
Akọwa Nkọwa
The reaction with the highest ΔH (change in enthalpy) would be the reaction between HCL and NaOH, which forms NaCL and H2O. This is because the formation of water releases energy in the form of heat, which is reflected in the positive ΔH value for this reaction. When an acid and a base react, they neutralize each other and form a salt and water, with the release of heat being a sign of an exothermic reaction.
Ajụjụ 14 Ripọtì
In order to electroplate spoon with silver, the arrangement of the electrolytic cell is?
Akọwa Nkọwa
Ajụjụ 15 Ripọtì
How many neutrons are present in atom with mass number and atomic number 37 and 17 respectively?
Akọwa Nkọwa
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.
Ajụjụ 16 Ripọtì
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
Ajụjụ 17 Ripọtì
Which of the following constitutes a mixture? I. Petroleum II. Rubber latex III. Vulcanizer’s solution IV. Carbon (iv) sulphide
Akọwa Nkọwa
Ajụjụ 18 Ripọtì
Which of the following roles does sodium chloride play in preparation? It
Akọwa Nkọwa
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.
Ajụjụ 19 Ripọtì
A chemical widely used as a fertilizer is?
Akọwa Nkọwa
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.
Ajụjụ 20 Ripọtì
Calcium forms complexes with ammonia because
Akọwa Nkọwa
The reason why calcium forms complexes with ammonia is that it has empty d-orbitals.
Ajụjụ 21 Ripọtì
The sub-atomic particles located in the nucleus of an atom are?
Akọwa Nkọwa
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.
Ajụjụ 22 Ripọtì
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
Akọwa Nkọwa
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.
Ajụjụ 23 Ripọtì
Akọwa Nkọwa
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.
Ajụjụ 24 Ripọtì
N2 O4 ? 2NO2 (? = -ve)
From the reaction above, which of these conditions would produce the highest equilibrium yield for N2 O4 ?
Akọwa Nkọwa
The highest equilibrium yield of N2O4 would be produced at low temperature and low pressure. In a chemical reaction, the position of the equilibrium can be influenced by changing the temperature or pressure. A decrease in temperature or an increase in pressure favors the side of the reaction with the fewer moles of gas (in this case, N2O4). This means that, if the temperature is low and the pressure is low, there will be more N2O4 at equilibrium, as the reaction will shift to the right to counteract the reduction in the concentration of N2O4. So, low temperature and low pressure would produce the highest equilibrium yield of N2O4.
Ajụjụ 25 Ripọtì
The following non-metal form acidic oxides with oxygen except?
Akọwa Nkọwa
An acidic oxide is an oxide that reacts with water to form an acidic solution. Non-metals have a greater tendency to form acidic oxides than metals. Therefore, among the given options, the non-metal that does not form an acidic oxide with oxygen would be the one that does not react with water to form an acidic solution. Out of the given options, chlorine is the non-metal that does not form acidic oxides with oxygen. Chlorine reacts with oxygen to form a number of oxides such as chlorine monoxide (Cl2O), chlorine dioxide (ClO2), and chlorine trioxide (ClO3), but none of these oxides react with water to form an acidic solution. Instead, they react with water to form oxyacids or oxoacids such as hypochlorous acid (HClO), chlorous acid (HClO2), and chloric acid (HClO3), which are stronger acids than the oxides. Therefore, the correct answer is chlorine.
Ajụjụ 27 Ripọtì
A colored gas that is known to be poisonous and can readily damage the mucous lining of the lungs is?
Akọwa Nkọwa
The colored gas that is known to be poisonous and can readily damage the mucous lining of the lungs is chlorine. Chlorine is a highly reactive chemical element that is used in the production of many everyday products, such as paper, textiles, and plastics. It is also used as a disinfectant in swimming pools and water treatment plants. Inhaling chlorine gas can cause severe respiratory problems, including coughing, chest pain, and difficulty breathing. Prolonged exposure to chlorine can cause lung damage, and in extreme cases, it can be fatal. Chlorine gas is also highly irritating to the eyes, skin, and mucous membranes. It is important to handle chlorine with caution and to use appropriate protective gear, such as gloves and respiratory masks, when working with it. Proper ventilation and monitoring of chlorine levels are also essential to prevent exposure to this toxic gas.
Ajụjụ 29 Ripọtì
Which of the following will act as both oxidizing agents and reducing agents?
Akọwa Nkọwa
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.
Ajụjụ 30 Ripọtì
Which of the following does NOT contain aluminum as a component?
Ajụjụ 31 Ripọtì
Which of the following statement is TRUE of the complete hydrolysis of a glyceride by sodium hydroxide?
Akọwa Nkọwa
The statement that is TRUE of the complete hydrolysis of a glyceride by sodium hydroxide is: - 3 moles of NaOH are required for each mole of glyceride. During the hydrolysis of a glyceride (a triglyceride), the ester bonds between the fatty acid chains and glycerol are broken by the action of a strong base like sodium hydroxide. This results in the formation of glycerol and the corresponding salts of fatty acids, which are commonly known as "soaps." The reaction can be represented by the following equation: Triglyceride + 3 NaOH → 3 soap + glycerol As per the equation, 3 moles of NaOH are required to hydrolyze one mole of glyceride, and 3 moles of soap and one mole of glycerol are produced. The use of concentrated sulfuric acid (H2SO4) is not essential for the completion of the reaction, but it can be used as a catalyst to speed up the reaction.
Ajụjụ 32 Ripọtì
There is a large temperature interval between the melting point and the boiling point of metal because:
Akọwa Nkọwa
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.
Ajụjụ 33 Ripọtì
The dehydration of CH3 CH2 CH2 CH2 OH will give?
Ajụjụ 34 Ripọtì
Hard water is water with high concentrations of dissolved ions, in particular calcium and
Akọwa Nkọwa
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.
Ajụjụ 35 Ripọtì
| 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?
Akọwa Nkọwa
Ajụjụ 36 Ripọtì
Alkanes are used mainly?
Ajụjụ 37 Ripọtì
Akọwa Nkọwa
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.
Ajụjụ 38 Ripọtì
A metal which can be used as sacrificial anode for preventing corrosion of length of iron pipe is
Ajụjụ 39 Ripọtì
Using the metal activity series, the metal that can liberate hydrogen gas from steam is?
Akọwa Nkọwa
The metal that can liberate hydrogen gas from steam is iron. The metal activity series is a list of metals in order of their reactivity, with the most reactive metals at the top and the least reactive metals at the bottom. When a metal is placed in a solution of steam (water vapor), the metal will react with the steam if it is more reactive than hydrogen. In this case, iron is more reactive than hydrogen, so it can displace hydrogen from the steam to form hydrogen gas. This reaction can be represented by the equation: Fe + H2O (steam) → FeO (iron oxide) + H2 (hydrogen gas) So, when steam is passed over iron, hydrogen gas is liberated and iron oxide is formed.
Ajụjụ 40 Ripọtì
Which of the following is used as a moderator to control nuclear fission?
Akọwa Nkọwa
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.
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