JAMB UTME - Chemistry - 2018
Ibeere 1 Ìròyìn
Which of the following statements is correct about the periodic table?
Awọn alaye Idahun
Ibeere 2 Ìròyìn
The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is
Awọn alaye Idahun
Ibeere 3 Ìròyìn
Which of the compounds is composed of Al, Si, O and H?
Awọn alaye Idahun
The compound composed of Al, Si, O and H is clay. Clay is a type of sedimentary rock that is made up of very small mineral particles, including hydrated aluminum silicates and other minerals such as quartz and feldspar. These minerals are rich in aluminum, silicon, oxygen, and hydrogen, which gives clay its unique chemical composition. Clay is formed through a process of weathering and erosion of rocks containing these minerals over a long period of time. As water and other natural forces break down the rocks, the mineral particles become suspended in water and are eventually deposited in sedimentary layers. Over time, these layers become compacted and cemented together, forming the solid clay deposits we see today. Therefore, the answer is option C: Clay.
Ibeere 4 Ìròyìn
A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by
Awọn alaye Idahun
Ibeere 5 Ìròyìn
An aqueous solution of a metal salt, M. gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia Therefore the cation in M is
Awọn alaye Idahun
Ibeere 7 Ìròyìn
Calculate the pH of 0.05 moldm?3 H2 SO4
Awọn alaye Idahun
To solve this problem, we need to use the formula for calculating the pH of a solution, which is: pH = -log[H+] where [H+] is the concentration of hydrogen ions in moles per liter. The given chemical equation is: H2SO4 + 2H2O → 2H3O+ + SO42- From this equation, we can see that one molecule of sulfuric acid (H2SO4) can donate two hydrogen ions (H+) to the solution, which means that the concentration of hydrogen ions is twice the concentration of sulfuric acid. Therefore, the concentration of hydrogen ions in this solution is: [H+] = 2 x 0.05 moldm^-3 = 0.1 moldm^-3 Now we can use the formula for pH: pH = -log[H+] pH = -log(0.1) pH = 1.00 Therefore, the pH of the solution is 1.00.
Ibeere 9 Ìròyìn
The boiling of fat and aqueous caustic soda is referred to as
Awọn alaye Idahun
The boiling of fat and aqueous caustic soda is referred to as saponification. Saponification is the process of converting fat into soap through a reaction with an alkaline substance, such as caustic soda. The reaction results in the formation of soap (a salt of a fatty acid) and glycerol. This process is important in the manufacture of soap, as it allows the fat to be converted into a useful cleaning product.
Ibeere 10 Ìròyìn
The situation obtained when a perfect gas expands into a vacuum is
Awọn alaye Idahun
Ibeere 11 Ìròyìn
The hydrogen ion concentration of a sample of orange juice is 2.0 X 10−11 moldm−3 . What is its pOH ? [log102 = 0.3010]
Awọn alaye Idahun
Ibeere 12 Ìròyìn
Which of the following metals cannot replace hydrogen from water or steam?
Awọn alaye Idahun
Ibeere 13 Ìròyìn
An element used in the production of matches is
Awọn alaye Idahun
The element used in the production of matches is sulphur. Matches are small sticks made of wood or cardboard with a chemical mixture at one end. This chemical mixture, called the match head, contains several compounds including sulphur. When the match is struck against a rough surface, the friction generates heat that ignites the sulphur in the match head, causing a flame. This flame then ignites the other compounds in the match head, which in turn ignites the wood or cardboard stick. Sulphur is an important component of the match head because it is highly flammable and burns easily. It also helps to ignite the other compounds in the match head. However, sulphur by itself is not a good fuel, which means that it cannot sustain a flame on its own. Therefore, it needs other combustible materials, such as potassium chlorate or phosphorus, to make the match head burn. Overall, sulphur plays a crucial role in the chemistry of matches and allows us to easily start fires for various purposes.
Ibeere 14 Ìròyìn
A substance that is used as a ripening agent for fruits is
Awọn alaye Idahun
The substance that is commonly used as a ripening agent for fruits is ethene. Ethene, also known as ethylene, is a natural plant hormone that is produced by fruits, especially during the ripening process. It is a colorless gas that can be easily synthesized and used as a ripening agent for fruits. When fruits are exposed to ethene, it triggers a series of biochemical reactions that accelerate the natural ripening process. This can help fruits to ripen faster and more uniformly, which is important for commercial purposes where fruits need to be sold quickly. The use of ethene as a ripening agent is regulated by food safety agencies, as excessive exposure to ethene can cause over-ripening and spoilage of fruits. However, when used in appropriate concentrations, ethene is a safe and effective way to promote the ripening of fruits.
Ibeere 15 Ìròyìn
A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that
Awọn alaye Idahun
Ibeere 18 Ìròyìn
According to the Kinetic Theory an increase in temperature causes the kinetic energy of particles to
Awọn alaye Idahun
The kinetic energy of particles increases with an increase in temperature. In the Kinetic Theory, temperature is related to the average kinetic energy of the particles in a substance. The higher the temperature, the faster the particles move, and the more energy they have. Think of it like this: if you throw a ball, it will have more energy and travel farther if you throw it harder. Similarly, if you heat up a substance, its particles will move faster and have more energy. So, the answer is that an increase in temperature causes the kinetic energy of particles to increase.
Ibeere 19 Ìròyìn
Which of the following pairs of substances will react further with oxygen to form a higher oxide?
Awọn alaye Idahun
Ibeere 20 Ìròyìn
During the electrolysis of copper II sulphate between platinum electrodes, if litmus solution is added to the anode compartment
Awọn alaye Idahun
During the electrolysis of copper II sulphate between platinum electrodes, if litmus solution is added to the anode compartment, the litmus will turn red and oxygen gas will be evolved. This is because during electrolysis, the positively charged copper ions (Cu2+) in the copper II sulphate solution are attracted to the negative cathode electrode, where they gain electrons and are reduced to form solid copper. At the same time, the negatively charged sulphate ions (SO42-) are attracted to the positive anode electrode, where they lose electrons and are oxidized to form oxygen gas and water. The litmus added to the anode compartment turns red because of the formation of oxygen gas, which is a highly reactive oxidizing agent that can react with the litmus to cause it to turn red. No hydrogen gas is evolved because hydrogen is produced at the cathode, which is in a separate compartment from the anode where the litmus is added.
Ibeere 21 Ìròyìn
Which of these alloys contains copper?
Awọn alaye Idahun
Bronze is the alloy that contains copper. Bronze is a metal alloy composed of copper and typically other elements such as tin, aluminum, silicon, or nickel. It is known for its strength, durability, and corrosion resistance. In fact, bronze is one of the earliest alloys created by humans, and it has been used for thousands of years to make tools, weapons, and decorative objects. Solder is an alloy of lead, tin, and sometimes other metals that is used to join metals together by melting the solder and allowing it to flow into the joint. Steel is an alloy of iron and carbon, and sometimes other elements like chromium, nickel, or manganese, that is known for its strength and durability. Permallory is a nickel-iron alloy with high magnetic permeability and low coercive force, which makes it useful in the production of electrical and electronic equipment. None of these alloys contain copper.
Ibeere 22 Ìròyìn
Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?
Awọn alaye Idahun
Ibeere 23 Ìròyìn
The refreshing and characteristic taste of soda water and other soft drinks is as a result of the presence of
Awọn alaye Idahun
Ibeere 24 Ìròyìn
If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density
Awọn alaye Idahun
Ibeere 25 Ìròyìn
In the preparation of oxygen by heating KCIO, in the presence of MnO2 only moderate heat is needed because the catalyst acts by 2
Awọn alaye Idahun
The presence of MnO2 acts as a catalyst in the reaction of KCIO2 to produce oxygen. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction itself. MnO2 acts by lowering the energy barrier of the reaction, which means it reduces the amount of energy required for the reaction to take place. This makes it easier for the reaction to occur, and thus the reaction proceeds at a faster rate. As a result, only moderate heat is needed to provide the initial energy required for the reaction to start. Therefore, the correct answer is: lowering the energy barrier of the reaction.
Ibeere 26 Ìròyìn
In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?
Awọn alaye Idahun
Ibeere 27 Ìròyìn
If one of the following oxides is heated with hydrogen or carbon using a bunsen burner. it is not reduced to the metal, Which one is it?
Awọn alaye Idahun
The oxide that cannot be reduced to the metal when heated with hydrogen or carbon using a Bunsen burner is magnesium oxide. Magnesium oxide is an ionic compound made up of positively charged magnesium ions and negatively charged oxygen ions. When heated with hydrogen or carbon, the oxygen ions are not easily removed from the compound. This is because the ionic bond between the magnesium and oxygen ions is very strong and requires a lot of energy to break. On the other hand, lead oxide, copper oxide, and tin oxide are all metal oxides and can be reduced to the metal by heating with hydrogen or carbon. This is because they have a weaker bond between the metal and oxygen ions, allowing the oxygen to be removed more easily when heated. In conclusion, magnesium oxide is the oxide that cannot be reduced to the metal when heated with hydrogen or carbon using a Bunsen burner.
Ibeere 28 Ìròyìn
3H2(g) + N2 ⇔ 2NH3(g) ; H= -ve
In the reaction above, lowering of temperature will
Ibeere 29 Ìròyìn
The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?
Awọn alaye Idahun
Ibeere 30 Ìròyìn
(I). 3CuO(s) + 2NH3(g) -----> 3Cu(s) + 3H2O(l) + N2(g)
(II). 2NH3(g) + 3Cl2(g) -----> 6HCl(g) + N2(g)
(III). 4NH3(g) + 3O2(g) -----> 6H2O(l) + N2(g)
The reactions represented by the equations above demonstrate the
Awọn alaye Idahun
Ibeere 31 Ìròyìn
The type of bonding in [Cu(NH3 )4 ]2+ is
Awọn alaye Idahun
The type of bonding in [Cu(NH3)4]2+ is coordinate bonding. Coordinate bonding (also known as dative covalent bonding) is a type of covalent bonding where one atom (in this case, the nitrogen atom in NH3) donates a pair of electrons to another atom or ion (in this case, the copper ion Cu2+). The donating atom is called the ligand, and the receiving atom or ion is called the central metal ion. In [Cu(NH3)4]2+, each ammonia molecule (NH3) donates a lone pair of electrons on the nitrogen atom to the copper ion, forming four coordinate bonds between the ligands and the central copper ion. The presence of coordinate bonds is indicated by the use of square brackets around the coordination compound, and the charge on the compound is indicated by the superscript outside the brackets. Therefore, the answer is option A: coordinate.
Ibeere 32 Ìròyìn
The elements in the periodic table are listed in order of increasing
Awọn alaye Idahun
Ibeere 33 Ìròyìn
What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O =16, H = 1]
Awọn alaye Idahun
The concentration of a solution containing 2g of NaOH in 100cm3 of solution is 0.40 moldm-3. This can be calculated by using the formula: molarity (M) = number of moles of solute / volume of solution (in liters) First, we need to calculate the number of moles of NaOH in the solution. The molar mass of NaOH is (23 + 16 + 1) = 40 g/mol. So, 2g of NaOH is equal to 2/40 = 0.05 moles. Next, we need to convert the volume of the solution from cm3 to liters. 1 cm3 = 0.001 liters, so 100 cm3 = 0.1 liters. Finally, we can calculate the molarity as follows: M = 0.05 moles / 0.1 liters = 0.5 mol/L = 0.50 moldm-3 So, the concentration of the solution is 0.50 moldm-3.
Ibeere 34 Ìròyìn
Sieving is a technique used to separate mixtures containing solid particles of
Awọn alaye Idahun
Sieving is a technique used to separate mixtures containing solid particles of different sizes. A sieve is a mesh or perforated screen that is used to separate particles based on their size. The mixture is poured onto the sieve, and the particles that are too large to pass through the holes are left on top, while the smaller particles fall through the holes and are collected below. This process allows for the separation of the different-sized particles, making it easier to purify or further process the mixture.
Ibeere 35 Ìròyìn
To what temperature must a gas at 273k be heated in order to double both its volume and pressure?
Awọn alaye Idahun
Ibeere 36 Ìròyìn
According to Charles' law, the volume of a gas becomes zero at
Awọn alaye Idahun
Charles' law states that the volume of a gas is directly proportional to its temperature, provided that the pressure remains constant. This means that as the temperature of a gas increases, its volume also increases. However, it is important to note that this law only applies to ideal gases, which are theoretical gases that perfectly follow the laws of thermodynamics. According to Charles' law, the volume of a gas becomes zero at absolute zero, which is approximately -273°C. At this temperature, the gas particles would have no kinetic energy and would be in their lowest energy state. The volume of a real gas would not actually become zero at absolute zero because the gas particles would have some residual intermolecular interactions that would prevent them from completely collapsing to a single point.
Ibeere 37 Ìròyìn
Aluminium does not react with either dilute or concentrated trioxonitrate (V) acid because
Awọn alaye Idahun
Ibeere 38 Ìròyìn
The number of electrons in the valence shell of an element of atomic number 14 is?
Awọn alaye Idahun
The number of electrons in the valence shell of an element can be determined by using the periodic table and the electron configuration of the element. The valence shell is the outermost shell that contains electrons that are involved in chemical reactions. For an element with atomic number 14, which is silicon, the electron configuration is 1s2 2s2 2p6 3s2 3p2. The valence shell of silicon is the third shell, which contains 3s2 and 3p2 electrons. Therefore, the number of electrons in the valence shell of silicon is 4 electrons.
Ibeere 39 Ìròyìn
A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].
Awọn alaye Idahun
The amount of substance liberated at an electrode during electrolysis is directly proportional to the quantity of electricity passed through the solution. This is known as Faraday's laws of electrolysis. The key to solving this problem is to recognize that the same quantity of electricity is used to liberate both silver and aluminum from their respective salts. We can use the ratio of their molar masses to determine the mass of aluminum liberated. The molar mass of silver (Ag) is 108 g/mol, while the molar mass of aluminum (Al) is 27 g/mol. This means that it takes four times as many moles of aluminum to make the same mass as one mole of silver. Since the same quantity of electricity liberates 3.6g of silver from its salt, it will liberate four times as many moles of aluminum. Therefore, the mass of aluminum liberated is: (4 moles of Al) x (27 g/mol) = 108 g So, the mass of aluminum liberated is 0.108 g, or 0.1 g to one significant figure. Therefore, the answer is option D: 0.3g.
Ibeere 40 Ìròyìn
Which of the following separation techniques can be employed in obtaining solvent from its solution?
Awọn alaye Idahun
The separation technique that can be employed in obtaining a solvent from its solution is evaporation. Evaporation is a process that involves heating a solution to vaporize the solvent, leaving behind the solute. The vaporized solvent can then be condensed and collected as a pure liquid. This technique is commonly used in industry and laboratory settings to recover solvents from solutions, as it is a simple and effective way to purify liquids. Distillation can also be used to separate a solvent from a solution, but it is a more complex process that involves boiling the solution and then condensing the vapors in a separate apparatus. Filtration and precipitation are not suitable for separating a solvent from a solution, as they are primarily used to separate solid particles from a liquid mixture.
