If an element has an atomic number 19, what is the element? If the mass number is 39, how many neutrons does it have? If it is a neutral atom how many electrons does it have?
Answer:
neutrons = 20
Explanation:
No. of Neutrons = Mass No. - Atomic No
= 39 - 19
=20
Answer:
1) What is the element? Potassium
2) how many neutrons does it have? 20
3) If it is a neutral atom how many electrons does it have? 39
Please mark as brainliest if answer is right
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Conduct research to identify two naturally occurring radioactive elements and two synthetic radioactive elements.
Natural radioactive elements are those that spontaneously radiate in nature and have an atomic number between 82 and 92. In dirt, air, water, rocks, plants, food, uranium—a radioactive element—can be discovered.
What makes certain substances radioactive?When an element's atoms contain excess neutrons or protons, the extra energy produced in the nucleus causes the atom to lose its equilibrium or become unstable. if and how radioactive particles can become stable. Radiation is produced by radioactive atoms' unstable nuclei.
What radiation is the most dangerous?Compared to beta and gamma particles, alpha particles represent the most dangerous internal threat. The most hazardous methods of exposure to radioactive elements that release alpha and beta radiation are ingestion, inhalation, absorption, and injection. Gamma radiation is the outside hazard that causes the most damage.
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Step 4: How many of each type of atom should react so that the electrons
lost will equal the electrons gained?
A. one potassium and one iodine
B. two potassium and one iodine
C. one potassium and two iodine
D. two potassium and three iodine
Answer:
A. one potassium and one iodine
Explanation:
K is a metal and I is a nonmetal, so K will lose electrons to form a cation and I will gain electrons to form an anion. Together, they will be bonded through an ionic bond. To determine how many electrons they gain or lose and how many atoms are in the chemical formula, we need to consider the octet's rule: an atom will gain, lose, or share electrons until it has 8 electrons in its valence shell.
K belongs to Group 1 in the periodic table and it has 1 valence electron. So, it will lose 1 electron to complete the octet. The resulting cation is K⁺.I belongs to Group 17 in the periodic table and it has 7 valence electrons. So, it will gain 1 electron to complete the octet. The resulting anion is I⁻.We need 1 K⁺ and 1 I⁻ to form the neutral salt KI.
The graph below shows the average number of sunspots seen between 1610 and 2009.
Based on the graph, which of these conclusions is most likely correct?
The global climate was colder than normal from 1650 to 1700.
The global climate was colder than normal from 1950 to 2000.
The global climate was hotter than normal from 1630 to 1650.
The global climate was hotter than normal from 1900 to 1930.
The global climate was colder than normal from 1650 to 1700. This conclusion is most likely correct. Therefore, option A is correct.
What is global climate ?Global climate refers to how heat and precipitation are distributed over a lengthy period of time on Earth's surface. The average temperature of the planet is kept at roughly 60°F (16°C) by heat from the sun, which is within the range required for biological life and the preservation of the planet's liquid water reserves.
Global climate change is the collective term for all the Earth's average long-term changes. Along with changing precipitation patterns and higher temperatures, these also include the consequences of global warming, such as: rising sea levels alpine glaciers are thinning.
Thus, option A is correct.
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Your question is incomplete probably your question was
The graph below shows the averaged sunspots from 1610 to 2007. The graph shows sunspot number on the y axis and years 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, and 2000 on the x axis. The graph rises and falls in a cyclic order in gaps of approximately 10 years. The number of sunspots observed in 1610 was 40, in 1650 it was 5, in 1700 it was 10, in 1750 it was 90 and the number of sunspots in 1800 was 50. The number of sunspots observed in 1850 was 130 and the number of sunspots in 1900 was 10. The number of sunspots observed in 1950 was 150 and the number of sunspots observed in 2000 was 30. Based on the graph, which of these conclusions is correct? Some of the previously warm regions became colder from 1650 to 1700. Some of the previously cold regions became warmer from 1600 to 1700. Some of the previously warm regions became warmer from 1610 to 1700. Some of the previously cold regions became colder from 1900 to 1950.
. If a balloon will rise off the ground when it contains 0.0226 mol of helium in a volume of 0.460 L, how many moles of helium are needed to make the balloon rise when its volume is 0.865 L? Assume that temperature and pressure stay constant.
The number of moles of helium (He) needed to make the balloon rise is 0.043 moles.
How to calculate number of moles?The number of moles of a gas can be calculated using the following expression:
V₁/n₁ = V₂/n₂
Where;
V₁ = initial volumen₁ = initial moles V₂ = final volumen₂ = final molesAvogadro’s law to predict what will happen to the volume of a sample of gas as we change the number of moles. Because V/n is a constant for any given sample of gas (at constant P and T).
At constant temperature and pressure the volume of a gas is directly proportional to the number of moles of gas.
0.46/0.0226 = 0.865/n
20.3539823n = 0.865
n = 0.043 moles
Therefore, 0.043 moles is the number of moles of the gas when the balloon rises.
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What is the number of moles of K+ ions are present in 250 mL of a 0.4M KCl solution?
a. 0.1 mol c. 0.62 mol
b. 0.16 mol d. 1.6 mol
The concentration terms are molality, normality and mole fraction. Molarity can be used to find out the ionic strength of any solution. Therefore, 0.025 is the number of moles of K+ ions are present in 250 mL of a 0.4M KCl solution.
What is molarity?Molarity can be calculated by dividing number of moles of solute by volume of solution in litre. Molarity is affected by temperature. Its unit is mole/liter. It measure the concentration of any solute in a solution.
Mathematically,
Molarity= number of moles of solute/volume of solution in litre
Substituting values in equation 1
0.4M=number of moles of solute/0.25
number of moles of solute=0.025moles
Therefore, 0.025 is the number of moles of K+ ions are present in 250 mL of a 0.4M KCl solution.
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How many total valence electrons are present
in the CH3Cl molecule? Please help
Answer:
I think the answer is 14 I am not sure
how do you test the methods of cleaning an oil spill while not risking the lives of the organisms
Answer:
Get a controlled environment, such as a pool or even a bowl. Pour some oil in it then you can test your solutions without causing any damage.
Explanation:
What could be the estimated atomic mass of Silicon?
A. 26.2 amu
B. 28.1 amu
C. 29.8 amu
D. 30.1 amu
Answer:
B. 28.1 amu
Explanation:
help
1. write the complete chemical symbol for the ion with 14 protons 15 neutrons and 18 electrons
2. write the complete chemical symbol for the ion with 27 protons 32 neutrons and 25 electrons
Answer:
a
Explanation:
The formation of ion occurs when an atom that is said to be neutral gains or losses electrons.
At the time it gains electrons, it is regarded that a negative ion (anion) is formed.
When it loses electron, it is regarded that a positive ion (cation) is formed.
Atomic number = No of protons and electrons occurring in a neutral atom.
Given that:
Protons = 14
electron = 18
Net Charge = no of proton - no of electron
= 14 - 18
= -4
Mass number = 14 + 15 = 29
So, the chemical symbol = [tex]Si^{-4}[/tex]
For ion with
27 proton, 32 neutrons and 25 electrons
Net charge = 27 - 25
= +2
Mass number = 27 + 32 = 59
Thus, the chemical symbol = [tex]Co^{+2}[/tex]
explaining how is it day time in the UAE and night time in the USA
Because of their different longitude.
Forensic biologist Warren is examining a substance found at a crime scene. Using a chemical test, he determines that glycogen is
present in the substance. What does this mean for his investigation?
The substance is from an animal source.
The substance is the poison ricin.
The substance is from a plant source.
The substance is a lipid.
Answer: the substance is from an animal source
Explanation:
What is the final temperature of the metal?
What is the temperature change of the water?
What is the temperature change of the metal?
"C
Answer:
1. The final temperature of the metal is 111 °C.
2. The change in the temperature of the water is 6.2 °C
3. The change in the temperature of the metal is 40.6 °C.
Explanation:
From the question given above, the following data were obtained:
Initial temperature of metal (Tₘ₁) = 70.4 °C
Initial temperature of water (Tᵥᵥ₁) = 23.6 °C
Equilibrium temperature (Tₑ) = 29.8 °C
1. Determination of the final temperature of metal.
We'll begin by calculating the change in temperature of the metal. This can be obtained as follow:
Initial temperature of metal (Tₘ₁) = 70.4 °C
Equilibrium temperature (Tₑ) = 29.8 °C
Change in temperature of metal (ΔTₘ) =?
ΔTₘ = Tₘ₁ – Tₑ
ΔTₘ = 70.4 – 29.8
ΔTₘ = 40.6 °C
Finally, we shall determine the final temperature of the metal. This can be obtained as follow:
Initial temperature of metal (Tₘ₁) = 70.4 °C
Change in temperature of water (ΔTₘ) = 40.6 °C
Final temperature of metal (Tₘ₂) =?
40.6 = Tₘ₂ – 70.4
Collect like terms
40.6 + 70.4 = Tₘ₂
111 = Tₘ₂
Tₘ₂ = 111 °C
Thus, the final temperature of the metal is 111 °C
2. Determination of the change in the temperature of the water.
Initial temperature of water (Tᵥᵥ₁) = 23.6 °C
Equilibrium temperature (Tₑ) = 29.8 °C
Change in temperature of water (ΔTᵥᵥ) =?
ΔTᵥᵥ = Tₑ – Tᵥᵥ₁
ΔTᵥᵥ = 29.8 – 23.6
ΔTᵥᵥ = 6.2 °C
Therefore, the change in the temperature of the water is 6.2 °C
3. Determination of the change in the temperature of the metal.
The change in the temperature of the metal is 40.6 °C.
Please solution 1 above for explanation.
Answer:
29.8 C
6.2 C
-40.6 C
:)
Explanation:
Which is true?
Capacity is the amount of liquid a container can hold. Volume is how much space an object takes up.
Volume is the amount of liquid a container can hold. Capacity is how much space an object takes up.
Capacity is the amount of solid a container can hold. Volume is how much space an object takes up.
Capacity is the amount of liquid a container can hold. Mass is how much space an object takes up.
Answer:
Capacity is the amount of liquid a container can hold. Mass is how much space an object takes up.
Explanation:
All the others are incorrect.
Describe why chemists needed to invent a new counting unit.
Answer:
Why do chemists use the mole as a counting unit? Because chemical reactions often involve large numbers of small particles, chemists use a counting unit called the mole to measure amounts of a substance. ... The discovery enabled scientists to classify certain chemical reactions as transfers of electrons between atoms.Explanation:
Chemical reactions often involve large numbers of small particles, chemists use a counting unit called the mole to measure amounts of a substance.
Why is counting so important?It is not possible to vell with a single atom or molecule because we
can't count them.
Chemists have set a number of particles with which to toil that is convenient. As molecules are very small.
Thus, chemists use a counting unit called the mole to measure the amounts of a substance.
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The volume of a gas at 2.0 atm is 3.0 L. What is the volume of the gas at 1.5 atm at the same temperature?
0.50 L
1.0 L
1.5 L
4.0 L
By applying Boyle's law, the new volume of this gas is equal to: D. 4.0 L.
Given the following data:
Initial volume = 3.0 L.
New pressure = 1.5 atm.
Initial pressure = 2.0 atm.
How to calculate the new volume?In order to calculate the new volume of this gas, we would apply Boyle's law. Mathematically, Boyle's law is given by this formula:
PV = k
P₁V₁ = P₂V₂
Where:
P represents the pressure.V represents the volume.Making V₂ the subject of formula, we have:
V₂ = (P₁V₁)/P₂
Substituting the given parameters into the formula, we have;
V₂ = (2.0 × 3.0)/1.5
V₂ = 6.0/1.5
V₂ = 4.0 L.
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Answer:
D. 4.0 Liters
Explanation:
I took the exam
how many moles in 185cm³ two moles solution
Answer:
4.44 moles
Explanation:
first u have to change the units into dm cube.
cm cube÷1000=dm cube
185cmcube÷1000= 0.185dm cube
24dm cube= 1 mole(formula)
0.185dm cube × 24dm cube=4.44 moles
How many atoms are in a sample of chromium with a mass of 31 grams? O a 2.4 x 1024 atoms of chromium b 3.6 x 1023 atoms of chromium 1.9 x 1026 atoms of chromium Od 1.5 x 1023 atoms of Chromium
Answer:
b. 3.66x10²³ atoms of chromium.
Explanation:
First we calculate how many moles are there in 31 grams of chromium, using its molar mass:
Molar Mass of Chromium = 51 g/mol (This can be found on any periodic table)31 g ÷ 51 g/mol = 0.608 molThen we calculate how many atoms are there in 0.608 moles, using Avogadro's number:
0.608 mol * 6.023x10²³ atoms/mol = 3.66x10²³ atomsThe correct answer is thus option b. 3.66x10²³ atoms of chromium.
The ____________________ is the organ associated with the sense of touch.
a.
nose
c.
heart
b.
liver
d.
skin
Please select the best answer from the choices provided
Which process transfers heat from a hot pavement to a person sitting on
Answer: The answer is Conduction
Answer:
Conduction
Explanation:
Conduction happens when materials or objects are in direct contact with each other. The molecules in the warmer object vibrate faster than the ones in the cooler object.
Which explanation describes the first part of a chemical reaction? Reactants collide to form products. Products collide to form reactants. Products collide to form a transition state. Reactants collide to form a transition state.
Answer:
Reactants collide to form a transition state.
Explanation:
So sorry if I’m wrong but I feel this is right
To solve such this we must know the concept of chemical reaction. The correct option is option B that is atoms in one compound switch places with atoms in another compound.
What is chemical reaction?Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.
There are so many types of chemical reaction reaction like combination reaction, double displacement reaction, combustion reaction, displacement reaction. "Reactants collide to form a transition state" describes the first part of a chemical reaction.
Therefore "Reactants collide to form a transition state" describes the first part of a chemical reaction. The correct option is option B.
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How many molecules of H2O are equivalent to 97.2g H2O
Answer:
3.25×10²⁴ molecules
Explanation:
From the question given above, the following data were obtained:
Mass of H₂O = 97.2 g
Number of molecule of H₂O =?
From Avogadro's hypothesis, we understood that:
1 mole of H₂O = 6.02×10²³ molecules
Next, we shall determine the mass of 1 mole of H₂O. This can be obtained as follow:
1 mole of H₂O = (2×1) + 16
= 2 + 16
= 18 g
Thus,
18 g of H₂O = 6.02×10²³ molecules
Finally, we shall determine the number of molecules in 97.2 g of H₂O. This can be obtained as follow:
18 g of H₂O = 6.02×10²³ molecules
Therefore,
97.2 g of H₂O = 97.2 × 6.02×10²³ / 18
97.2 g of H₂O = 3.25×10²⁴ molecules
Thus, 97.2 g of H₂O contains 3.25×10²⁴ molecules.
Please help me fill in the blanks
Sublevels are indicated by letters s, p, d, and f.
How do write Electronic configuration?
Electron configurations have a standard notation that tells you the principle energy levels and sublevels that electrons occupy. here is Sulphur:
The atomic number of Sulphur is 16.
the electronic configuration of Sulphur is 1s2 2s2 2p6 3s2 3p4.
The 4s sublevel has lower energy than the 3d sublevel,
so, it fills next.
Which four different electron configurations are there?One orbital can house a maximum of two electrons, and there are four different types of orbitals (s, p, d, and f). More electrons can be held in the p, d, and f orbitals since they contain various sublevels. According to its location on the periodic table, each element's electron configuration is distinct.
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Which of the following is a polar substance?
O Water
O Grease
O Gasoline
O Oil
A 1.00 L volume of HCl reacted completely with 2.00 L of 1.50 M Ca(OH)2 according to the balanced chemical equation below. 2HCl + Ca(OH)2 Right arrow. CaCl2 + 2H2O What was the molarity of the HCl solution? 0.375 M 1.50 M 3.00 M 6.00 M
Mass can be calculated by using moles which can be further calculated from multiplication of Molarity to volume. Therefore, the molarity of the HCl solution is 3M. the correct option is option C.
What is molarity?
Molarity can be calculated by dividing number of moles of solute by volume of solution in litre. Molarity is affected by temperature. Its unit is mole/litre. It measure the concentration of any solute in a solution.
Other concentration terms are molality, normality and mole fraction. Molarity can be used to find out the ionic strength of any solution
Mathematically,
2HCl + Ca(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] CaCl[tex]_2[/tex] + 2H[tex]_2[/tex]O
Molarity of HCL× Volume of HCL=Molarity of Ca(OH)[tex]_2[/tex] ×Volume of Ca(OH)[tex]_2[/tex]
Molarity of HCL× 1.00 L=1.50 M× 2.00 L
Molarity =3M
Therefore, the molarity of the HCl solution is 3M. the correct option is option C.
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3 What does the term electrolysis mean?
?
Answer:
Electrolysis is the passing of a direct electric current through an electrolyte producing chemical reactions at the electrodes and decomposition of the materials. The main components required to achieve electrolysis are an electrolyte, electrodes, and an external power source.
Explanation:
Answer:
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell.
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I am new here...
thanks ^^
list five examples of acidic oxides
8 acidic oxides, take your pick <3
Aluminium oxide.
Silicon dioxide.
Phosphorus oxides.
Sulfur oxides.
Chlorine oxides.
Iron oxides.
Chromium oxides.
Vanadium oxides
What is the empirical formula for the compound H4O2?
Answer:
Explanation:
Dear student, there is no sufficient information to calculate the empirical formula but we will explain what Empirical Formula is all about.
An empirical formula is made up of symbols that denote the elements in a complex, such as H for hydrogen and O for oxygen, as well as subscripts that indicate the number of atoms from each constituent element.
The empirical formula is the atoms in a complex with the lowest whole number ratio. The precise number of atoms in a single molecule is not necessarily shown.
On a cold day you may make a cup of hot chocolate. What is the solute in hot chocolate? A. Cocoa powder B. Heat C. Steam D. Mug
Answer:
A
Explanation:
Solute is what is being dissolved.
Solute is cocoa powder when we make a cup of hot chocolate ,therefore option (a) is correct.
What do you mean by the term solute ?A solute is a substance that is dissolved in a solvent to form a solution.
The concentration of a solute in a solution is a measure of how much of the solute is dissolved in the solvent.
Characteristics of solute -:
The solute cannot be separated from the solution by filtration .It is composed of one phase only. Solutes in solution are measured by their concentration. The concentration of a solute is the amount of solute divided by the total volume of solution.Solute is cocoa powder when we make a cup of hot chocolate ,hence option (a) is correct.
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Which of these is an example of a physical property?
A. Chlorine oxidizes bacterial cells.
B. Chlorine gas is yellow-green in color.
C. Chlorofluorocarbons (CFC's) react with ozone (O₂).
D. Potassium ignites when placed in water.
Answer:
B. Chlorine gas is yellow-green in color.