Answer:
The answer is: D
Explanation:
A. They have the same number of electron energy shells. Is false, all the elements are in different periods so, they have different number of lectron energy shells.
B. They are all Halogens. No, is wrong, halogens are F, Cl ,Br
C. They have the same number of electrons. is wrong, if they had the same number of electrons they must be they same element and they aren't the same.
D. They are all Noble gases. Yes, it's true they are noble gases, they are the first group in the periodic table from the right.
Answer:
D-They are all noble gases
Explanation:
They have the same valency
when methanol, ch3oh, is dissolve in water, a nonconducting solution reslults. when acetic acid, ch3cooh, diisolves in water, the solution is weakly conductng and acidic in nature. describe what happens upon dissolution in the two ases, and account for the different results
Answer and Explanation:
When methanol (CH₃OH) dissolves in water, the following equilibrium takes place:
CH₃OH + H₂O ⇄ CH₃O⁻ + H₃O⁺
The dissociation constant is about 10⁻¹⁶ (very very small), so methanol practically does not dissociate in its ions in water, thus the solution does not conduct electricity (because there is a very small quantity of ions).
By other hand, acetic acid (CH₃COOH) dissociates in water as follows:
CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺
and its dissociation constant is about 10⁻⁵, which is not negligible. So, there is a considerable quantity of ions in solution and they can conduct electricity.
Methanol doesn't ionize in water and therefore forms a non-conductive solution, while acetic acid does ionize partially, making it a weak conductor and imparting an acidic character to the solution. Also, differences in solution behaviour are due to inherent properties of the respective molecules.
Explanation:When methanol (CH3OH) is dissolved in water, it does not produce ions; hence it is a nonconducting solution. Methanol is a covalent compound and does not ionize in water. Hence, no ions are formed and it does not conduct electricity.
On the other hand, when acetic acid (CH3COOH) dissolves in water, its molecules ionize slightly, forming CH3CO2- ions and H3O+ ions. Because the number of ions is less than that created by strong electrolytes, it conducts electricity weakly and is a weak electrolyte.
Furthermore, the ionization of acetic acid also generates H3O+ ions, making the solution acidic. Additionally, acetic acid can form dimers, which are pairs of acetic acid molecules, under certain conditions, contributing to its acidic nature.
The differences in solution behavior are due to the properties of the molecules themselves - methanol is a simple alcohol and does not tend to ionize, while acetic acid is a carboxylic acid that has an acidic hydrogen which it can donate (although not as readily as a strong acid).
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A 3.35 gram sample of an unknown gas is found to occupy a volume of 1.64 L at a pressure of 706 mmHg and a temperature of 59 °C. Assume ideal behavior. The molar mass of the unknown gas is ___________ g/mol.
Answer: The molar mass of the unknown gas is 59.8 g/mol
Explanation:
According to the ideal gas equation:-
[tex]PV=nRT[/tex]
P= Pressure of the gas = 706 mmHg = 0.93 atm (760mmHg=1atm)
V= Volume of the gas = 1.64 L
T= Temperature of the gas = 59°C=(59+273)K=332 K (0°C = 273 K)
R= Value of gas constant = 0.0821 Latm\K mol
[tex]n=\frac{PV}{RT}=\frac{0.93\times 1.64L}{0.0821 \times 332}=0.056moles[/tex]
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]
[tex]0.056=\frac{3.35g}{\text {Molar mass}}[/tex]
[tex]{\text {Molar mass}}=59.8g[/tex]
Thus the molar mass of the unknown gas is 59.8 g/mol
The molar mass of the unknown gas is calculated using the ideal gas law equation. After converting the pressure to atmospheres and temperature to Kelvin, the molar mass is found to be 57.46 g/mol.
Explanation:To calculate the molar mass of the unknown gas, we will use the ideal gas law equation PV = nRT, where P is pressure, V is volume, n is the amount of moles, R is the ideal gas constant, and T is temperature in Kelvin. We can rearrange the formula to solve for n (moles) and then use the mass of the gas to find its molar mass.
First, let's convert the given pressure and temperature to standard units. Pressure in atmospheres (atm) is 706 mmHg × (1 atm / 760 mmHg) = 0.9295 atm. Temperature in Kelvin (K) is 59 °C + 273 = 332 K.
Now we can use the ideal gas law equation:
PV = nRT
0.9295 atm × 1.64 L = n × 0.0821 L·atm·K¹·mol¹ × 332 K
Solving for n (moles), we get n = 0.0583 mol.
The molar mass (MM) is the mass of the gas divided by the number of moles:
Molar Mass = Mass / Moles
Molar Mass = 3.35 g / 0.0583 mol = 57.46 g/mol
Which characteristic is found in liquids and gases? A. Has a fixed volume B. Particles stay in a fixed position C. No particle movement D. Takes the shape of the container
Answer:
The answer to your question is letter D.
Explanation:
A. Has a fixed volume This is not the right answer, liquids and gases take the shape of the container in which they are.
B. Particles stay in a fixed position This answer is wrong, this characteristic is of solids but not of liquids and gases.
C. No particle movement This characteristic is also of solids, in liquids and gases the particles can move.
D. Takes the shape of the container. This is the right answer, liquids and gases take the shape of the container.
Answer:
D :)
Explanation:
Which equation using element symbols correctly describes the reaction: "Two molecules of sodium hydroxide plus one molecule of sulfuric acid reacts to form one molecule of sodium sulfate and 2 molecules of water?"
A. 2NaOH+H2SO4→Na2SO4+2H2O
B. 2NaOH+H2O→Na2SO4+2H2SO4
C. Na2SO4+H2SO4→NaOH+H2O
D. NaOH+H2SO4→Na2SO4+H2O
Final answer:
The correct equation for the reaction between two molecules of sodium hydroxide and one molecule of sulfuric acid is 2NaOH+H2SO4→Na2SO4+2H2O.
Explanation:
The equation that correctly describes the reaction where two molecules of sodium hydroxide react with one molecule of sulfuric acid to form one molecule of sodium sulfate and two molecules of water is: 2NaOH+H2SO4→Na2SO4+2H2O. This equation illustrates a neutralization reaction whereby sulfuric acid (a strong acid) reacts with sodium hydroxide (a strong base) to produce sodium sulfate, a salt, along with water. This is an example of a reaction with a diacid, where two moles of the base are required to fully neutralize one mole of the diacid, resulting in a salt and water as the products.
If a lab requires each a lab group (3 students) to have 25 ml of a solution and it takes 15 grams of AgNO₃ cuprous nitrate, to make 1 liter of solution, how many grams are needed to make enough solution?
Answer:
0.375 grams are needed to make 25 mL solution.
Explanation:
Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1 l of solution = 15 g.
1 L = 1000 mL
Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1000 mL of solution = 15 g
Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 1 mL of solution:
[tex]=\frac{15}{1000} g[/tex]
Mass of [tex]AgNO_3[/tex] cuprous nitrate required to make 25 mL of solution:
[tex]=\frac{15}{1000} \times 25 g=0.375 g[/tex]
0.375 grams are needed to make 25 mL solution.
Which of the following processes is exothermic?
a. The reaction associated with DH°f for an ionic compound the ionization of a lithium atom.
b. The sublimation of dry ice (CO2(s))
c. The breaking of a Cl-Cl bond
d. All of the above processes are exothermic
Answer:
a. The reaction associated with DHºf for an ionic compound
Explanation:
An exothermic process is a process that loses heat for the surroundings, so the temperature of the system must decrease, and ΔH must be negative.
DHºf or ΔHºf of an ionic compound is always negative because the final energy is always lower than the initial. It happens because of the stability of the bond, the system wants a lower energy state to be stable.
The ionization of a lithium atom occurs with the gain of energy, which is given to the electron, so it may give off the atom. So it's an endothermic process.
To change the state of a solid to a gas (sublimation), the compound must gain heat, its temperature must increase, so it's always an endothermic process.
To break a covalent bond it's necessary the gain of energy, so it's an endothermic process.
Answer:A
Explanation:
The enthalpy change of formation for an ionic compound is calculated from the Born-Haber cycle. Using the Hess law of constant heat summation. The result is always negative (exothermic) because energy is given out when the new lattice is formed.
A 75 gram bar of gold is cut into three equal pieces. How does the density of each piece compare to the density of the original bar?
1. Each piece is 1/3 the density of the original bar
2. Each piece is the same as the density of the original bar
Answer:
You should know that density is the relation between, mass and volume as it is described in this equation: d = m/v. As the mass doesn't change in each piece, you will see that volume is less than the original, that's why each piece is 1/3 the density of the original bar or, you can also see, that you have increase by 3, the density original.
Explanation:
Which components of the atom have no charge? None of the components have charges. neutrons electrons protons
Answer:
The answer to your question is: neutrons
Explanation:
None of the components have charges. This is incorrect because the atoms is composed by three particles, neutrons, electrons and protons, and the characteristic of an atom is that its particles at least some are charged.
neutrons: are particles located in the nucleus and they diminish the repulsion forces among the protons. They don't have any charge
electrons : they are located in the shells are are negative charged.
protons: they are located in the nucleus and are positive charged.
Answer:
neutrons
Explanation:
Hemoglobin is a large protein molecule that is responsible for carrying oxygen through the blood. Iron ions are a relatively small component of hemoglobin. There are four Fe2+ions that are part of the much larger hemoglobin structure. In a single red blood cell there are 2.50x108molecules of hemoglobin. If a single Fe2+ion has an atomic radius of 75.1 pm and a redblood cell has a volume of 95 μm3, what percentage of the total red blood cell volume is taken up by Fe2+ions?
approximately [tex]\( 6.22 \times 10^5 \% \)[/tex] of the total red blood cell volume is taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions.
To find the percentage of the total red blood cell volume taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions, we first need to calculate the volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions and then express it as a percentage of the total volume of the red blood cell.
1. Calculate the Volume Occupied by [tex]\( \text{Fe}^{2+} \)[/tex] Ions:
The volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions can be calculated based on the number of ions and their atomic radius.
Each [tex]\( \text{Fe}^{2+} \)[/tex] ion can be considered as a sphere, and its volume [tex](\( V_{\text{Fe}^{2+}} \))[/tex] can be calculated using the formula for the volume of a sphere:
[tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi r^3 \][/tex]
where r is the atomic radius of [tex]\( \text{Fe}^{2+} \)[/tex] ions.
Given that the atomic radius of [tex]\( \text{Fe}^{2+} \)[/tex] ions is [tex]\( 75.1 \, \text{pm} \)[/tex] [tex](or \( 75.1 \times 10^{-12} \, \text{m} \))[/tex], we can calculate the volume of one [tex]\( \text{Fe}^{2+} \)[/tex] ion.
Then, multiply this volume by the number of [tex]\( \text{Fe}^{2+} \)[/tex] ions present in a single red blood cell to find the total volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions.
2. Calculate the Percentage of the Total Red Blood Cell Volume:
After obtaining the volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions, divide it by the total volume of the red blood cell and multiply by 100 to express it as a percentage.
Let's perform the calculations:
1. Calculate the Volume Occupied by [tex]\( \text{Fe}^{2+} \)[/tex] Ions:
[tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi (75.1 \times 10^{-12} \, \text{m})^3 \][/tex]
[tex]\[ V_{\text{Fe}^{2+}} = \frac{4}{3} \pi (4.468 \times 10^{-10} \, \text{m}^3) \][/tex]
[tex]\[ V_{\text{Fe}^{2+}} = 2.363 \times 10^{-9} \, \text{m}^3 \][/tex]
Now, we need to find the total volume occupied by [tex]\( \text{Fe}^{2+} \)[/tex] ions in the red blood cell:
[tex]\[ V_{\text{total Fe}^{2+}} = (2.50 \times 10^8 \, \text{molecules}) \times (2.363 \times 10^{-9} \, \text{m}^3/\text{ion}) \][/tex]
[tex]\[ V_{\text{total Fe}^{2+}} = 5.908 \times 10^{-1} \, \text{m}^3 \][/tex]
2. **Calculate the Percentage of the Total Red Blood Cell Volume:**
Given that the volume of the red blood cell is [tex]\( 95 \, \mu\text{m}^3 \) (or \( 95 \times 10^{-18} \, \text{m}^3 \))[/tex], we can calculate the percentage:
[tex]\[ \text{Percentage} = \frac{V_{\text{total Fe}^{2+}}}{V_{\text{RBC}}} \times 100 \][/tex]
[tex]\[ \text{Percentage} = \frac{5.908 \times 10^{-1} \, \text{m}^3}{95 \times 10^{-18} \, \text{m}^3} \times 100 \][/tex]
[tex]\[ \text{Percentage} \approx 6.22 \times 10^5 \% \][/tex]
Therefore, approximately [tex]\( 6.22 \times 10^5 \% \)[/tex] of the total red blood cell volume is taken up by [tex]\( \text{Fe}^{2+} \)[/tex] ions.
Identify the oxidation number of carbon in the compound lithium carbonate.
Answer:
The answer to your question is: +4
Explanation:
Oxidation number of carbon in Li₂CO₃
To know the oxidation number of Carbon, first find the oxidation number of Li and Oxygen.
Li is located in group IA in the periodic table, and all the elements that belong to this group have an oxidation number of +1.
O is located in group VIA in the periodic table, all the elements of this group have an oxidation number of -2.
Also, consider that the sum of the oxidation numbers in a neutral molecule equals zero.
Then
Lithium = +1 x 2 = +2
Oxygen = -2 x 3 = -6
+2 + Carbon oxidation number - 6 = 0
Carbon oxidation number = 6 -2
Carbon oxidation number = 4
The oxidation number of carbon in lithium carbonate is +4.
Given:
The compound - lithium carbonate
To find :
The oxidation number of carbon in the given compound.
Solution:
The formula of lithium carbonate = [tex]Li_2CO_3[/tex]
Number of lithium atoms = 2Number of carbon atoms = 1Number of oxygen atoms = 2Let the oxidation number of carbon be x.
The oxidation number of lithium is = +1
The oxidation number of oxygen = -2
The overall charge on the compound's molecule = 0
[tex]2\times (+1)+x+3\times (-2)=0\\\\+2+x-6=0\\\\x=+6-2=+4[/tex]
The oxidation number of carbon in lithium carbonate is +4.
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Scientists infer that early North American humans hunted the mastodon. Carbon-14 dating of the rib bone indicates that 2.4 half-lives have passed since the mastodon was killed. Approximately how many years ago did the mastodon die?
Answer:
d
Explanation:
The mastodon was estimated to have died around 13,752 years ago, as deduced using Carbon-14 dating. This period corresponds to when early North American humans likely hunted large games, including woolly mammoths using group cooperation and advanced tools.
Explanation:Understanding the life and death of a mastodon involves knowing the process of Carbon-14 dating and using this method to estimate the time-frame of the mastodon's demise. Carbon-14 undergoes radioactive decay and has a half-life of approximately 5730 years. In this problem, it is stated that 2.4 half-lives have passed since the mastodon was killed. Therefore, by multiplying the half-life of Carbon-14 (5730 years) by the number of half-lives that have passed (2.4), we can estimate that the mastodon died around 13,752 years ago.
This timescale fits into the period when early North American humans were known to have hunted large game, such as the woolly mammoths. Both archaeological evidence and cave paintings suggest coordinated hunting efforts with the use of sophisticated tools. The simultaneous occurrence of human migration, climate changes, and habitat reduction has been detected in this time frame, adding to the plausibility of human hunting leading to the extinction of these large animals.
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The mass number of an atom is 15, and its atomic number is 7. The atom probably has... 8 neutrons in the nucleus. about as much mass in electrons as in protons. at least 15 electrons. 7 units of negative charge in the nucleus. 7 electrons in the nucleus.
Answer: Option (a) is the correct answer.
Explanation:
Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.
For example, given atom has mass number as 15 and its atomic number is 7.
Therefore, number of neutrons present in it will be calculated as follows.
Mass number = no. of protons + no. of neutrons
15 = 7 + no. of neutrons
no. of neutrons = 15 - 7
= 8
Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.