PLEASE HELP!!
Use the periodic table to identify each of the elements below as an alkali metal or an alkaline earth metal.
Rb:
alkali metal
alkaline earth metal
Rubidium is a alkali metal.
Answer:
Rb is an alkali metal.
Explanation:
The elements characterized by having a single electron in its outermost orbital (s) are called alkali metals or simply alkaline metals.
Due to the presence of this electron, they are chemically very reactive because they have a tendency to lose this electron. In other words, their high reactivity is due to the fact that they form chemical bonds with many types of substances and elements and do so easily. This is due to its high electronegativity.
Like all metals, they are very good thermal and electrical conductors. But in comparison, alkali metals are soft and have a low melting point due to their metallic bond. This link is quite weak because it is the external electrons that are responsible for the bond and in these metals there is only one electron per atom.
The alkali metals are located in group 1 of the periodic table and are: lithium (Li), sodium(Na), potassium(K), rubidium(Rb), cesium(Cs) and francium(Fr).
A ballon is filled with 35 L of air at 2.0 atm. If the pressure is increase to 3.5 atm, what is the new volume?
Answer:
20 L
Step-by-step explanation:
Since temperature is constant, we can use Boyle’s Law.
p₁V₁ = p₂V₂ Divide each side by p₂
V₂ = V₁ × p₁/p₂
=====
Data:
p₁ = 2.0 atm; V₁ = 35 L
p₂ = 3.5 atm; V₂ = ?
=====
Calculations:
V₂ = 35 × 2.0/3.5
V₂ = 20 L
How does fluorine's electronegativity compare to the electronegativity of oxygen and chlorine?
The electronegativity of fluorine compare to the electronegativity of oxygen and chlorine as below
Fluorine has the highest electronegativity than oxygen and chlorine.
Explanation
Generally the electronegativity increase across the period ( from the left to the right) and decreases down the group.
Both oxygen and fluorine are in period 2 in periodic table. since fluorine is on fur right side as compared to oxygen , fluorine has higher electronegativity than oxygen.Answer:
Fluorine is a smaller atom so when it forms a covalent bond, the shared electrons are closer to the nucleus and there is less shielding, electronegativity of oxygen is greater.
Which statement is true about the elements present in a pure substance?
A They maintain their chemical properties.
B They are composed of many compounds.
C They can be separated by physical methods.
D They can only be separated by chemical methods.
Answer: Option (D) is the correct answer.
Explanation:
An element is defined as a substance that contains atoms of one type.
For example, a piece of sodium metal will contain only atoms of sodium.
Therefore, it is a pure substance. Whereas a compound is a substance that consists of two or more different atoms in similar composition.
For example, [tex]CaCl_{2}[/tex] is a compound.
When elements change into compounds then they tend to change their chemical properties.
Hence, we can conclude that the statement they can only be separated by chemical methods, is true about the elements present in a pure substance.
is utensils a substance homogeneous mixture or heterogeneous mixture
Final answer:
Utensils made of metal are typically homogeneous mixtures, while utensils made of plastic can be heterogeneous mixtures.
Explanation:
A utensil is not a substance but an object that is used to prepare or eat food. However, if you are referring to the materials that utensils are made of, such as metal or plastic, then they can be considered as mixtures. Utensils made of metal, for example, are typically a mixture of different metals, such as stainless steel or aluminum alloy. These metal mixtures can be considered as homogeneous mixtures because their composition is uniform throughout. On the other hand, utensils made of plastic can be considered as heterogeneous mixtures because they can have different additives and fillers mixed in with the plastic polymer.
Which of the following molecules experience dipole-dipole forces as its strongest IMF? A) H2 B) SO2 C) NH3 D) CF4 E) BCl3
Answer: [tex]NH_3[/tex]
Explanation:
a) [tex]H_2[/tex]: This is a non polar covalent compound which are held by weak vanderwaal forces of attraction.
b) [tex]SO_2[/tex]: This is a covalent compound which is polar due to the presence of lone pair of electrons and are held by dipole-dipole forces of attraction.
c) [tex]NH_3[/tex]: These are joined by a special type of dipole dipole attraction called as hydrogen bond. It forms between electronegative nitrogen atom and hydrogen atom and is the strongest interaction.
d) [tex]CF_4[/tex]: This is a covalent compound and is non polar which are held by weak vanderwaal forces of attraction.
e) [tex]BCl_3[/tex]: This is a covalent compound and is non polar which are held by weak vander waal forces of attraction.
NH3 (Ammonia) experiences dipole-dipole forces as its strongest IMF due to its polar nature and the uneven distribution of electron density within the molecule.
Explanation:The student's question asks to identify which molecule experiences dipole-dipole forces as its strongest intermolecular force (IMF). Dipole-dipole forces occur in polar molecules where there is an uneven distribution of electron density that creates dipoles, meaning one end of the molecule is slightly positive while the other end is slightly negative. Given the list of molecules, NH3 (Ammonia) experiences dipole-dipole forces as its strongest IMF because it is a polar molecule with a trigonal pyramidal structure, leading to a net dipole moment. Ammonia has a nitrogen atom with a lone pair that causes the molecule to be asymmetrical and polar, resulting in dipole-dipole attraction between molecules.
Balance the following reaction: AI2O3+HCI-AICI3+H2O
the balanced equation is:
Al2O3 + 6HCl -> 2AlCl3+3H2O
Can someone please define the Cohesion of water?
cohesion is the "stickiness" that water molecules have for each other and for other substances.
Hope this helped :)
A mixture is made up of evenly spaced atoms of copper and silver. Is this mixture a solution? Explain your answer.
Answer: This is a mixture.
Explanation:
A solution consists of solute (which can be solid, liquid or gas) mixed in a given amount of solvent.
A mixture is a combination of two or more substances which are not present in a definite proportion.
We are given two solids: copper and silver.
As, they are not present in definite proportion hence, they are considered as mixtures.
Which of the following methods estimates geologic events by comparing the objects to the layer of Earth they were discovered in? Fossil dating Geologic dating Radioactive dating Relative dating
The answer is; Relative dating
This type of dating is not concerned with determining the absolute age of rock. It compares between rock layer and determines which is younger or older in comparison. Therefore relative dating is significant in arranging geologic events based on the stratigraphy of rock layers.
Answer: Relative dating
Explanation:
Relative dating is a technique of identifying the age of the material whether fossil or rocks by comparing them with the surrounding materials. This method takes into consideration the order of the geological events took place on earth. This can be done by stratigraphy. In stratigraphy the layers of the rocks and sediments are compared to determine the age of the object (fossil, rock). This method does not help in determining the exact or absolute age of the object.
What energy conversion is taking place when working of a hair dryer
When you rub your hands together on a cold day, you use friction to transform
A. mechanical energy into thermal energy.
B. thermal energy into nuclear energy.
C. nuclear energy into electrical energy.
D. electrical energy into electromagnetic energy.
A. mechanical energy to thermal energy
Is LiCl nonpolar or polar?
LiCi is an ionic compound, and ionic compounds are considered polar.
what is tihe minimum temperature needed to dissolve 130 grams of KNO3 in 100 grams of water
The minimum temperature needed to dissolve 130 grams of [tex]KNO_{3}[/tex] in 100 grams of water is the solubility of [tex]KNO_{3}[/tex] at that particular temperature.
Solubility is the maximum amount of solute that can dissolve in a solvent at a given temperature. A [tex]KNO_{3}[/tex] solubility chart or data table must be used to estimate the minimum temperature needed to dissolve 130gm of [tex]KNO_{3}[/tex] in 100gm of water.
Given:
Mass of [tex]KNO_{3}[/tex] = 130 gm,
Mass of water = 100 gm.
Let's assume that the solubility of [tex]KNO_{3}[/tex] in 100gm of water is 80gm at 20°C. The solubility limit will be exceeded (130gm > 80gm) if we attempt to dissolve 130gm of [tex]KNO_{3}[/tex] in 100gm of water at 20°C, producing an unsaturated solution. To find the minimum temperature needed for complete dissolution, we need to find the temperature at which the solubility of [tex]KNO_{3}[/tex] is equal to or greater than 130gm. If we refer to the solubility chart and find that at 30°C, the solubility of [tex]KNO_{3}[/tex] is 130gm in 100gm of water, then the minimum temperature required is 30°C.
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Based on your answer in part B, arrange the five elements in order of their reactivity. Drag the most reactive element to the top and the least reactive element to the bottom. Tiles magnesium iron copper zinc hydrogen
Answer: Order of the elements from most reactive to least reactive is:
Mg > Zn > Fe > H > Cu
Explanation: Reactivity of the elements is the tendency of the elements to loose or gain electrons with ease.
As, all the given elements are metals, so the metals which will loose electrons easily will be more reactive. To study the reactivity of metals, we use reactivity series.
The metals which are more reactive are placed on the top of the reactivity series and which are less reactive are placed at the bottom.
Hence, the order of the elements from most reactive to least reactive is:
Mg > Zn > Fe > H > Cu
Reactivity series is attached below.
Answer:
magnesium
Zinc
Iron
hydrogen
copper
Explanation:
Just took the course activity
On a position-versus-time graph, where is time usually shown?
A. at the origin
B. along the x-axis
C. along the y-axis
time is usually on the x axis while position is on the y axis>
hope this helped ^_^
Answer:
On a position-versus-time graph, along the x-axis (option b) is time usually shown.
Explanation:
One way to describe and study the movements is by means of graphs that represent distance-time (distance as a function of time), speed-time (speed as a function of time) and acceleration-time (acceleration as a function of time).
Then, as the displacements are made while time passes, the description of the movement is facilitated by making a graph of position versus time. In the vertical axis the positions that the body occupies are usually represented and in the horizontal axis the time. Similarly, velocity or acceleration can be represented versus time, where the horizontal axis is time and the vertical axis is velocity or acceleration.
Taking into account that the horizontal axis belongs to the x axis and the vertical axis to the y axis:
On a position-versus-time graph, along the x-axis (option b) is time usually shown.
Before it was launched, a helium-filled balloon had a pressure of 201 kPa at a temperature of 27°C. At an altitude of 15,000 m, the pressure had decreased to 2.5 kPa and the temperature had dropped to -14 °C. The volume of the balloon increased to 59.3 m3. What is the original volume of the balloon? please help
The original volume of the balloon is approximately 29 L.
Explanation:To calculate the original volume of the helium-filled balloon, we can use the combined gas law equation: PV/T = PV/T. Let's assume the unknown original volume as V1. Conversion of the temperatures from Celsius to Kelvin gives us T1 = 27 + 273 = 300K and T2 = -14 + 273 = 259K. Plugging the given values into the equation, we have (201 kPa)(59.3 m3)/300K = (2.5 kPa)(V1)/259K. Solving for V1, we find the original volume of the balloon to be approximately 0.029 m3 or 29 L.
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To solve for the original volume of the balloon, we can use the Ideal Gas Law. After converting the temperatures to Kelvin, we can rearrange the formula of the Ideal Gas Law to solve for the original volume. Doing this, we find that the original volume is approximately 1.73 cubic meters.
Explanation:To solve this physics question, we need to use the Ideal Gas Law that states PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. In this case, we assume that the number of moles doesn’t change and the R is a constant. Therefore, we can simplify the law to the formula P1V1/T1=P2V2/T2 to find the original volume of the balloon.
Firstly, you need to convert the temperatures from Celsius to Kelvin by adding 273.15. That gives us 300.15K for 27°C and 259.15K for -14°C. The initial pressure (P1) is 201 kPa, the final pressure (P2) is 2.5 kPa, and the final volume (V2) is 59.3 m3.
So applying the equation P1V1/T1 = P2V2/T2, we can solve for V1, the original volume:
V1 = (P2*V2*T1)/(P1*T2) = (2.5 kPa*59.3 m3*300.15K)/(201kPa*259.15K)
This gives us the original volume as V1 = 1.73 m3.
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Which expression represents the percent by mass of nitrogen in NH 4 NO 3 ?
a. 28 g N / 80 g NH 4 NO 3 × 100%
b. 14 g N / 80 g NH 4 NO 3 × 100%
c. 80 g NH 4 NO 3 / 28 g N × 100%
d. 80 g NH 4 NO 3 / 14 g N × 100%
Answer: a) [tex]\frac{28gN}{80gNH_4NO_ 3}\times 100\%[/tex]
Explanation: Mass percentage is defined as the ratio of the mass of the particular element to the total mass of the substance multiplied by 100.
[tex]{\text{mass percentage}=\frac{\text{mass of the element}}{\text{Total mass}}\times {100}[/tex]
mass of nitrogen[2 atoms of N] = 28 g
Total mass of [tex]NH_4NO_ 3=2\times {\text {Mass of nitrogen}}+4\times {\text {mass of hydrogen}}+3\times {\text {mass of oxygen}}[/tex]
[tex]=2\times 14+4\times 1 +3\times 16=80 g[/tex]
[tex]{\text{mass percentage}=\frac{28}{80}\times {100}\%[/tex]
The correct percent by mass of nitrogen in NH4NO3 is given by the expression 28 g N / 80 g NH4NO3 * 100%.
Explanation:The expression that represents the percent by mass of nitrogen in NH4NO3 is determined by dividing the total mass of nitrogen in the compound by the total mass of the compound and then multiplying by 100%. Nitrogen has a molar mass of 14 g/mol, and there are two nitrogen atoms in NH4NO3. So, the total mass of nitrogen is 14 g/mol x 2 = 28 g/mol. Meanwhile, the molar mass of NH4NO3 is 80 g/mol. Therefore, the correct expression is 28 g N / 80 g NH4NO3 * 100%, or option (a).
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Which MOST closely defines population density?
A. the number of organisms of a species per unit area
B. it determines how many organisms can survive in a given population
C. the number of organisms in a population that an ecosystem can sustain
D. it consists of all organisms of a species living together in a given area at given time
your answer should be
A. the number of organisms of a species per unit area
Brainliest?
Answer: Option (A) is the correct answer.
Explanation:
Usually, density is defined as mass present in per unit volume.
Mathematically, Density = [tex]\frac{mass}{volume}[/tex]
Since density is directly proportional to mass so, more is the mass of an object more will be its density.
Similarly, population in terms of density is the number of organisms of a species per unit area.
Thus, we can conclude that out of the given options the number of organisms of a species per unit area MOST closely defines population density.
What is the oxidation number of Mn in Ca(MnO4)2
Answer:
+ 7.
Explanation:
We have general rules to assign the oxidation numbers:
Rule 1: The oxidation number of an element alone in its free (uncombined) state is zero.
For example, Al(s) or Zn(s).
This is also true for elements found in nature as diatomic (two-atom) elements as: H₂, O₂, Cl₂, or I₂.
and also for sulfur, found as: S₈.
Rule 2: The oxidation number of a monatomic (one-atom) ion is the same as the charge on the ion,
For example: Na⁺ = +1, S⁻² = -2.
Rule 3: The sum of all oxidation numbers in a neutral compound is zero. The sum of all oxidation numbers in a polyatomic (many-atom) ion is equal to the charge on the ion.
Rule 4: The oxidation number of an alkali metal (group IA) in a compound is +1; the oxidation number of an alkaline earth metal (group IIA) in a compound is +2.
Rule 5: The oxidation number of oxygen in a compound is usually –2.
If, however, the oxygen is in a class of compounds called peroxides.
(for example, hydrogen peroxide), then the oxygen has an oxidation number of –1. If the oxygen is bonded to fluorine, the number is +1.
So, for our problem Ca(MnO₄)₂:
The sum of all oxidation numbers in a neutral compound is zero.The oxidation no. of Ca which is in (group IIA) = +2.The oxidation no. of O = -2.∴ oxidation no. of Ca + 2[(oxidation no. of Mn) + 4(oxidation no. of O) = 0.
(+2) + 2[(oxidation no. of Mn) + (- 8)] = 0.
2[(oxidation no. of Mn) + (- 8)] = - 2.
[(oxidation no. of Mn) + (- 8)] = -1.
∴ (oxidation no. of Mn) = - 1 + 8 = + 7.
+7 is the oxidation number of manganese atom (Mn) in Ca(MnO₄)₂.
What does oxidation number tells about?Oxidation number of any substance will tell about the import and export number of electrons from that substance.
Given compound is Ca(MnO₄)₂, this is a neutral compound means no charge is present on the compound. Oxidation number of Calcium (Ca) is +2, oxidation number of oxygen atom (O) is -2 and let the oxidation number of manganese (Mn) be x.
Total sum of the oxidation number of all atoms equals to the whole charge of the compound and calculation for oxidation number will be calculated as:
+2 + 2[x + 4(-2)] = 0
2 + 2x - 16 = 0
2x = 16 - 2
2x = 14
x = 7
Hence, +7 is the oxidation number.
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What is magma? a. The molten mixture of rock-forming substances, gases, and water from the mantle.. c. Hardened lava on the surface of the Earth. b. Liquid rock that reaches the surface. d. All of the above Please select the best answer from the choices provided
Answer: A The molten mixture of rock-forming substances, gases, and water from the mantle..
Explanation:
Compare photons and electrons. Which of the following statements is true?
Photon is a packet of light energy. Both photon and electron contribute mostly to the quantum mechanics of the atom. Every particle in quantum mechanical model is explained as dual natured, that is has both particle and wave nature. Photons exhibit wave light properties like diffraction, interference, etc.,At the same time they exhibit particle properties like having a definite momentum and position. Similarly electrons and other microscopic particles exhibit both particle and wave nature.
Therefore, the correct answer is:
Both photons and electrons display particle and wave-like behaviour.
can an excited lithium atom give off photos of light?
Yes or no
YYYEAAA
100% bro
Hope that help
What mass of acetylene gas, C2H2, would be produced by complete reaction of 3.75g of calcium carbide
The mass of C2H2 produced by the reaction of 3.75g of CaC2 can be calculated using the balanced chemical equation and the molar masses of CaC2 and C2H2. The number of moles of CaC2 and C2H2 can be determined, and then multiplied by their respective molar masses to find the mass of C2H2 produced.
Explanation:To answer the question, we need to use the balanced chemical equation for the reaction between calcium carbide (CaC2) and water (H2O):
CaC2 (s) + 2H2O (l) → C2H2 (g) + Ca(OH)2 (s)
From the equation, we can see that 1 mole of calcium carbide reacts to produce 1 mole of acetylene gas.
Now, we need to calculate the number of moles of calcium carbide using its molar mass:
Molar mass of CaC2 = 40.08 g/mol + 12.01 g/mol × 2 = 64.10 g/mol
Mass of CaC2 = 3.75
Number of moles of CaC2 = Mass of CaC2 / Molar mass of CaC2 = 3.75 g / 64.10 g/mol = 0.0585 mol
Since 1 mole of CaC2 produces 1 mole of C2H2, the number of moles of C2H2 produced is also 0.0585 mol.
Finally, we can calculate the mass of C2H2 produced using its molar mass:
Molar mass of C2H2 = 12.01 g/mol × 2 + 1.01 g/mol × 2 = 26.04 g/mol
Mass of C2H2 = Number of moles of C2H2 × Molar mass of C2H2 = 0.0585 mol × 26.04 g/mol = 1.52 g
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Which sub shell is likely to be filled after the rest of the sub shells at a particular energy level? 1. p
2. f
3.d
4.s
The subshell thats likely to be filled is s subshell
after the rest of the subshells at a particular energy level.
1. p
2. f
3.d
4.s
Answer:
2.f
Explanation:
At a particular energy level, say energy level 4. So lets compare subshells within the particular shell or energy level. Comparing 4s, 4p, 4d and 4f. Subshell s has the lowest energy and subshell f has the highest energy. So 4s orbital will be filled first, followed by 4p, 4d and 4f. This is in accrdance to Aufbau principle.
Therefore the f subshell is likely to be filled after the rest of the sub shells at a particular energy level are filled.
balance 2Mg +O2 = 2MgO
The chemical equation [tex]2Mg + O_{2} = 2MgO[/tex] reflects the principle of conservation of mass, showing an equal number of atoms for each element on both sides of the equation, thus balancing it.
Explanation:The balance of the chemical equation [tex]2Mg + O_{2} = 2MgO[/tex] shows the principle of conservation of mass in chemistry. This principle states that the quantity of matter does not change in a chemical reaction.
Here, we have 2 atoms of magnesium (Mg) reacting with 1 molecule of oxygen ([tex]O_{2}[/tex]) to form 2 molecules of magnesium oxide (MgO). If you count the number of atoms of each element on both sides of the equation, you can see the balance: 2 magnesium atoms and 2 oxygen atoms on both sides.
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The given equation 2Mg + O₂ = 2MgO is already balanced, as there are equal number of each type of atom on the reactants and the product side.
Explanation:To balance the chemical equation 2Mg + O₂ = 2MgO, we need to ensure that the number of molecules or atoms for each element on the reactant side (left) is the same as on the product side (right). This is in accordance with the Law of Conservation of Mass which states that matter cannot be created or destroyed. In this particular equation, we have 2 molecules of Magnesium (Mg) and one molecule of Oxygen (O₂) combining to give 2 molecules of Magnesium Oxide (MgO). If we inspect the equation, we'll see it's already balanced because the number of Mg and O atoms are same on both sides.
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all isotopes of uranium have how many protons
The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%)
Hope This Helped
A solid is cooled to a very low temperature. Assuming the mass remains constant, how, if at all, does this affect the density of the solid?
Enter your answer in the space provided
it is making a new form so the density would be the same because water becoming into ice a solid are the same thing.
when a solid is cooled, its molecules slow down n vibrate less. usually its volume will decrease. as the mass remains constant and density = mass/volume, density will decrease.
Please Help!
Complete and balance the following equation: Cd(NO3)2 + NH4Cl
((Include explanation please! I cant find how to do it and I need the explanation...))
CdCl2+2NH4NO3
It is substitution reaction
Cd is metal with 2+ which connect with Cl(-)
NO3 with NH4 form salt
Answer:
Cd(NO₃)₂ + 2NH₄Cl → CdCl₂ + 2NH₄NO₃
Explanation:
The reaction given is a double replacement reaction, which means that the reactants will dissociate and the ions will be changed between them. So, let's identify the ions.
At Cd(NO₃)₂, the metal Cd has cation Cd⁺², and the anion is NO₃⁻ (the number of ions is changed and the cation is the first to appear in the formula). At NH₄Cl, the cation is NH₄⁺ and the anion is Cl⁻, so the products are CdCl₂ and NH₄NO₃ (the cation comes first, and the charges are replaced between them).
So, the reacion will be:
Cd(NO₃)₂ + NH₄Cl → CdCl₂ + NH₄NO₃
To balance the equation, all the elements must have the same number on both sides, thus we need to multiply NH₄Cl and NH₄NO₃ by 2:
Cd(NO₃)₂ + 2NH₄Cl → CdCl₂ + 2NH₄NO₃
As you move down group one of the periodic table, what happens to the atomic radii? They increase, because of the higher number of occupied energy levels. They increase, because of the stronger attraction between electrons and the nucleus. They decrease, because of the weaker effective nuclear charge. They decrease, because of the lower number of protons.
The correct answer is the atomic radius increase because of the higher number of occupied energy levels.
Atomic radius increases when going down a group. The valence electrons hold the higher levels because of the enhancing quantum number (n). As a consequence, the valence electrons get further away from the nucleus with the increase in n. The electron shielding inhibits these outer electrons from getting fascinated towards the nucleus. Therefore, they are held, and the resulting atomic radius is greater.
Answer:
they increase, because of the higher number of occupied energy levels
Explanation: