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
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Help me please please i is in middle school need help ple
the answer is that it is a
What contains a single element 1. Acid/Base 2. Redox 3. Precipitation
Answer:
hydrogen ion dissolve in water is acid and hydroxide ion dissolve in water is basi
the recation in which oxidation and reduction goes side by side is redox redaction
Please help. Will give brainliest
Answer:
the answer to this is 71.0 grams of chlorine
An unknown substance is obtained by police. The forensics laboratory has
determined it is made of nitrogen and oxygen. If 74.66 grams are nitrogen
and the police obtained a 250 gram sample, what is the percent
composition of oxygen in the sample?
Answer:
70.0 %
Explanation:
Step 1: Given data
Mass of nitrogen (mN): 74.66 gMass of the compound (mNxOy): 250 gStep 2: Calculate the mass of oxygen (mO) in the compound
The mass of the compound is equal to the sum of the masses of the elements that form it.
mNxOy = mN + mO
mO = mNxOy - mN
mO = 250 g - 74.66 g = 175 g
Step 3: Determine the percent composition of oxygen in the sample
We will use the following expression.
%O = mO / mNxOy × 100%
%O = 175 g / 250 g × 100% = 70.0 %
What would be the cathode in a magnesium and zinc galvanic cell?
O A. Mg2+
OB. Zn(s)
OC. Zn²+
OD. Mg(s)
The correct answer is C. Zn²+. In a magnesium and zinc galvanic cell, the anode is the magnesium (Mg(s)) and the cathode is the zinc (Zn²+).
What is zinc galvanic cell?A zinc galvanic cell is an electrochemical device that uses a zinc anode and a cathode of a different material, usually copper, to produce electricity. The reaction that occurs in the cell is a redox reaction, which involves the oxidation of zinc at the anode and the reduction of copper at the cathode.
Zn²+. In a magnesium and zinc galvanic cell, the anode is the magnesium (Mg(s)) and the cathode is the zinc (Zn²+). In this cell, the magnesium metal is oxidized to form Mg2+ ions which are released into the solution. The zinc ions (Zn²+) are then reduced to zinc metal (Zn(s)) at the cathode.
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Answer: B
Explanation:
Please help me I really need the help
Thermal energy is the sum of all the potential and kinetic energy of the atoms within a system that is responsible for its temperature.
How to conclude the Electro negativity?Friction transforms other forms of energy into thermal energy. Atoms are the building blocks of matter. Atoms are composed of subatomic particles called protons, neutrons, and electrons.Periodic trends are patterns on the periodic table that illustrate elements’ characteristics.Significant trends are atomic radius, metallic reactivity, electronegativity, electron affinity, and ionization energy.
Atomic radius and metallic reactivity trends: They increase when they move down a group and left across a period.Electronegativity, electron affinity, and Ionization energy trends: They increase when they move up a group and right across a period.
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Alleles are different forms of which genetic structure?
A. DNA
B. Cells.
C. Genes
D. Chromosomes
Answer:
answer is c
Allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.
____________Polar regions get less of the sun's direct rays, they are the coldest climates on Earth. A because , B although, C Howerer, D Consequently / what best word fits in the blank space what makes sense.
Answer:
Because Polar regions get less of the sun's direct rays, they are the coldest climates on Earth.
Explanation:
26. The water of the surface of the ocean is termed surface currents and moves in a regular pattern. They don't depend on the weather and move heat around Earth. What two things create surface currents?
A sample of helium was compressed at 35 °C from a volume of 0.5 L to 0.25 L where the pressure is 500 mmHg. What was the original pressure?
Answer:
The ideal gas law is a formula that relates the pressure, volume, temperature, and number of moles of a gas. It can be expressed as:
PV = nRT
where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the gas constant, and T is the temperature in Kelvin.
Since the number of moles and the temperature are constant in this problem, we can rearrange the formula to solve for the pressure:
P = (nRT) / V
Plugging in the known values, we get:
P = (nRT) / V
= (n * R * (35 + 273)) / 0.25 L
= (n * R * 308 K) / 0.25 L
We are given that the pressure is 500 mmHg and the volume is 0.25 L at this pressure, so we can set these equal:
500 mmHg = (n * R * 308 K) / 0.25 L
Solving for n, we get:
n = (500 mmHg * 0.25 L) / (R * 308 K)
We know that the pressure and volume of the gas at its original state are what we are trying to solve for. Let's call the original pressure P_0 and the original volume V_0. We can then express the relationship between the original and final state of the gas as:
P_0 * V_0 = n * R * T
Substituting the expression we found for n and the known values, we get:
P_0 * V_0 = ((500 mmHg * 0.25 L) / (R * 308 K)) * R * 308 K
Solving for P_0, we get:
P_0 = (500 mmHg * 0.25 L) / (R * 308 K) * (R * 308 K) / V_0
= (500 mmHg * 0.25 L) / (V_0)
Since V_0 = 0.5 L, we can substitute this value to get:
P_0 = (500 mmHg * 0.25 L) / (0.5 L)
= 500 mmHg / 2
= 250 mmHg
Therefore, the original pressure of the gas was 250 mmHg.
What is the molecular formula of a compound with a molecular mass of 63.0g and an empirical formula of CH3O
Answer:
I think first molar mass of ch3o which is 31
Explanation:
The indicator methyl red has different molecular structures at high and low pH.
a. True
b. False
Answer:
a. True
Explanation:
Methyl red is an indicator widely used in quality control of oxides as Zinc oxide in the titration with sulfuric acid.
As is used in titrations of acid-base reactions the indicator change in colour. Is red when the pH < 4.4 (Acidic Solutions) and is yellow when pH > 6.2 (Neutral-Basic solutions).
A change in colour means the structure of the indicator is changing with pH. Thus, the answer is:
a. TrueWhen was the "Permian Era"?
Answer:
298.9 million years ago - 251.902 million years ago
Explanation:
It might be in the 2011 Earth Science Review Packet so maybe go check that out
Plz help me : Copper (I) chloride CuCl is made up of:
A. all metals
B.all nonmetais
C. Metal and nonmetal
Cells grouped together to make a specific part of the body of a plant or animal are called: an organism photosynthesis a tissue
Answer:
THE CORRECT ANWER IS ;Cells make up tissues, tissues make up organs, and organs make up organ ... All the systems of the body work together to keep an organism up and running. ... out a particular function, and groups of organs with related functions make up the ... Connective tissue supports and, as the name suggests, connects other tissues.
Explanation:
Answer: The correct answer to this question is "a tissue.
Explanation: "Tissue is a term used to describe a group of cells that have similar structure and function and work together to carry out a specific function in the body of a plant or animal.For example, muscle tissue is made up of muscle cells that work together to help the body move, while nervous tissue is made up of nerve cells that transmit signals throughout the body.An organism is a living entity that can carry out all of the basic life processes, while photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to produce food in the form of glucose.
Calculate the pH of the solution produced by adding 10mL of 1M hydrochloric acid to 1L of a solution which is 0.1M acetic acid and 0.1M in sodium acetate (Ka = 1.75 x 10-5 molL-1. Comment on the variation in pH.
A buffer solution is one in which the pH of the solution is "resistant" to small additions of either a strong acid or strong base. Buffers usually consist of a weak acid and its conjugate base, in relatively equal and "large" quantities. Calculations are based on the equation for the ionization of the weak acid in water forming the hydronium ion and the conjugate base of the acid. "HA" represents any weak acid and "A-" represents the conjugate base.
HA(aq) + H2O(l) --> H3O+(aq) + A-(aq)
Ka = [H3O+][A-]
How many calcium ions are in 0.9 mol of CaCl2?
× 10 Ca2+ ions Enter your answer in scientific notation.
Answer: There are [tex]5.42 \times 10^{23}[/tex] [tex]Ca^{2+}[/tex] ions present in 0.9 mol of [tex]CaCl_{2}[/tex].
Explanation:
According to the mole concept, there are [tex]6.022 \times 10^{23}[/tex] atoms present in one mole of a substance.
As here, 0.9 mol of [tex]CaCl_{2}[/tex] are present. Also, there is only one atom of Ca is present in a molecule of [tex]CaCl_{2}[/tex].
Hence, calcium ions present in 0.9 mol of [tex]CaCl_{2}[/tex] are calculated as follows.
[tex]No. of ions = 1 \times 0.9 \times 6.022 \times 10^{23}\\= 5.42 \times 10^{23}[/tex]
Thus, we can conclude that there are [tex]5.42 \times 10^{23}[/tex] [tex]Ca^{2+}[/tex] ions present in 0.9 mol of [tex]CaCl_{2}[/tex].
A sample of an unknown gas has a mass of 0.116 g. It occupies a volume of 25.0 mL at a temperature of 127°C and has a pressure of 155.3 kPa. Calculate the molar mass of the gas.
Answer:
The molar mass of the gas is 99.4 g/mol
Explanation:
Ideal gas law PV=nRT. P=155.3 T=127+273= 400K V=25.0 Gas constant=8.314 Now substiture the values into the equation n=PV/RT
n= (155.5kPa x 25.0mL x 1l/1000mL)/ 8.312l*KPa/mol*K x 400K
n= 0.001167 mol
Molar mass= Mass/ Number of moles
= 0.116g /0.001167 mol
= 99.4 g/mol
when might the BAC of a dead body be misleading or unhelpful
Answer: Blood alcohol levels at autopsy are valid up to 48 hours after death when simple principles are observed in the collection and storage of samples. Alcohol levels in samples of blood taken from the intact heart are as significant as levels of blood from the femoral veins.
Explanation:
Answer:
If the victim was submerged in water
Explanation:
order these elements by decreasing electron affinity:
Na, Al, S, K, F
Answer:
increasing to decreasing:
F--- S--- Al--- Na--- K
not sure...
how many grams of hexane(C6H14) would be need to make 562 of carbon dioxide
The mass of hexane, C₆H₁₄ that would be needed to produce 562 grams of carbon dioxide, CO2 is 183 g
How do I determine the mass of hexane, C₆H₁₄ needed?We'll begin by writing the balanced equation for the reaction.
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
The following are obtained from the equation:Molar mass of C₆H₁₄ = 86 g/molMass of C₆H₁₄ from the balanced equation = 2 × 86 = 172 g Molar mass of CO₂ = 44 g/molMass of CO₂ from the balanced equation = 12 × 44 = 528 gFrom the balanced equation above,
528 g CO₂ were produced from 172 g of C₆H₁₄
With the above information, we shall determine the mass of hexane, C₆H₁₄ needed to produce 562 g CO₂. Details below:
From the balanced equation above,
528 g CO₂ were produced from 172 g of C₆H₁₄
Therefore,
562 g of CO₂ will react to produce = (562 × 172) / 528 = 183 g of C₆H₁₄
Thus, the mass of hexane, C₆H₁₄ needed is 183 g
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The name of an alcohol side chain is known as an alkoxy group. True or false?
Does sublimation change chemical or physical change
Answer:
Yes, sublimation is a physical change because it involves a change of state from solid to gas of a substance when it is heated.
Reactants are an acid and a base, which one describes this? 1. Acid base 2. Redox 3. Precipitation 4. Combustion
Answer:
The answer is 1. acid-base
Explanation:
This is pretty self-explanatory, when an acid and base react, it is called an acid-base reaction. Redox reactions are where two reactants exchange electrons, precipitation reaction is where a solid is formed, and combustion reaction is where a compound is reacted with oxygen so none of those can be the answer.
2. The nonmetals in the Groups 16 and 17________
a) lose electrons when they form ions
b) gain electrons making them an anion
c) all have ions with a -1 charge
d) end in -ate
All of the ions in groupings 16 and 17 of nonmetals have a charge of -1. Spontaneous non-metals include brittle both thermally & electrically insensitive compounds.
What other names do non-metals have?Non-metals are elements that frequently gain electrons during chemical processes to generate anions. These substances are electronegative ones. They lack luster, are fragile, and are poor heat- and electricity-conductors (except graphite). Non-metals come in solid, liquid, or gaseous forms.
What 20 nonmetals are there?Lithium, Beryllium, Sodium, Mg, Aluminum, Potassium, & Calcium are the minerals within the first twenty elements. Hydrocarbons, Helium, Carbo, Nitrogen, Oxygen, Hydrochloric acid, Neon, Phosphorous, Sulphur, Chlorinated, and Argon now comprise the non-metals that comprise the first twenty elements.
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which statements describe what happen in a redox reaction?
a. one atom gains electrons and one loses electrons
b. the cations on two substances trade places
c. electrons move from one substance to another
d. there are two oxidation reactions
Answer:
A or C
Explanation:
I don't know if I'm correct but I think it's A or C you don't have to choose them.
which nucleus experiences a stronger net force holding its protons and neutrons togeter unanium or or barium
Answer:
Uranium experiences a stronger net force holding its protons and neutrons together than barium.
Explanation:
Global climate change is
a.
a politically motivated deception generated by scientists with an environmentalist agenda.
b.
hotly debated by a deeply divided scientific community.
c.
a hypothesis that is not yet well supported by scientific evidence.
d.
understood by science to be a fact, and as largely the result of human activities.
why is oxygen more electronegative than nitrogen
Answer:
Oxygen has 8 protons in the nucleus while nitrogen only has 7. A bonding pair will experience more attraction from the oxygen's nucleus than from nitrogen's, and so the electronegativity of oxygen is greater.
Fe2O3 + 6HCl → 2FeCl3 + 6H20 How many atoms of FeCl3 will be produced if 9.3 x 1023 atoms of HCl are used for this reaction? 6.7 x 1023 atoms FeCl3 3.1 x 1023 atoms FeCl3 9.3 x 1023 atoms FeCl3 1.2 x 1023 atoms FeCl3
Answer:
3.1x10²³
Explanation:
I'm going to answer the question assuming the number of molecules of FeCl₃ is asked, rather than the number of atoms.
Fe₂O₃ + 6HCl → 2FeCl₃ + 6H₂OFirst we convert 9.3x10²³ atoms of HCl into moles of HCl, using Avogadro's number:
9.3x10²³ atoms ÷ 6.023x10²³ atoms/mol = 1.54 mol HClThen we convert 1.54 moles of HCl into moles of FeCl₃, using the stoichiometric coefficients of the reaction:
1.54 mol HCl * [tex]\frac{2molFeCl_3}{6molHCl}[/tex] = 0.51 mol FeCl₃Finally we calculate how many FeCl₃ molecules are there in 0.51 moles:
0.51 mol * 6.023x10²³ molecules/mol = 3.4x10²³ moleculesThe closest option is 3.1x10²³.
The number of atoms produced is four times the number of FeCl₃ molecules produced.