The correct answer to the question is option C. Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Group 18 of the periodic table are known as the noble gas family. Their outermost shell is completely filled.
Members of the group 18 includes:
1. Helium (He)
2. Neon (Ne)
3. Argon (Ar)
4. Krypton (Kr)
5. Xenon (Xe)
6. Radon (Rn)
Among this group, only Helium (He) has a valence electron of 2. Other members of the group has a valence electron of 8.
Helium is part of the group 18 because its outermost shell is completely filled by its 2 electrons.
Therefore, option C gives the right answer to the question as helium only have 2 valence electrons while other members of the group has 8 valence electrons.
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how many times larger is 45000 than 0.0045?
Answer:
10,000,000
Explanation:
45000÷0.0044
=10,000,000
Answer:
10,000,000 times larger.
Explanation:
Multiply 0.0045 by 10,000,000 to get 45000. Or, Divide 45000 by 0.0045 to get 10,000,000.
Helppppp….. is this right?
Answer:
Yes, it is correct.
Explanation:
400 cm = 4 m
40 m = 40 m
0.4 km = 400m
Therefore, 400 cm < 40 m < 0.4 km
Answer:
Explanation:
400 centimeter....... smallest
0.4 kilometer .............. middlest
40 meter..................... greatest
Nhiệt phân hoàn toàn 1,88g Cu(NO3)2.Khí bay ra cho hấp thụ vào H2O tạo thành 2 l dd A. Dd A có pH= ?
Answer: theo mình thì mình làm như sau
cu(no3)2 nhiệt phân hết
\Rightarrow nNO2= 0,02mol
nO2=0,005mol
khi hấp thụ O2 và NO2 vào nước ta có
2NO2 + 1/2 O2\Rightarrow 2HNO3
phản ứng là vừa đủ nên
nHNo3= 0,02 mol
pH HNO3=2
khi cho 0,001mol NaOH vào thì phản ứng trung hòa
H+ + OH- \Rightarrow H20
nHNO3=0,02/20=0,001
nhận thấy nH+ =nOH- nên phản ứng vừa đủ
pH của dd Y=7
theo mình giải là như vậy
Explanation:
Calculate the no. of moles in 25gm of calcium phosphate
Plz Fast Urgent
Answer:
0.162 mol
Explanation:
n=m/M
M= 20*3 + 15*2 + 8*4*2
M=154 g/mol
n=25g/154g/mol
n=0.162 mol
The number of moles in 25 grams of calcium phosphate is 0.162 mol.
What are moles?Mole is a SI unit that is used to measure the quantity of any substance in a specific amount. To calculate the moles, we will divide the mass of the substance by the molar mass of that substance.
n = m/M
Calcium phosphate is a chemical compound that contains calcium and phosphorus or phosphoric acid, and it is used to treat the low calcium in the body and thyroid and parathyroid.
The molar mass of calcium sulfate is 154 g/mol
The mass of calcium sulfate is 25 grams
Putting the value in the equation
n = m/M
n = 25g / 154 g/mol = 0.162 mol
Thus, the moles of calcium sulfate are 0.162 mol.
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Read the information in the table below:
Reaction
Description Energy to IS break bonds is more tha renergy release to form bonds Energy to break bonds is less than energy release to form bonds
Which type of reaction is represented by B?
Answer: Exothermic
Explanation: The energy of the reactants is leass than that of the products. Conservation of energy means that the excess is given off, or exothermic.
Which of the following would electrolysis NOT be used for?
A. Producing electricity
B. Extracting reactive metals
C. Plating metals onto other metals
D. Producing hydrogen gas
Answer:
D
Explanation:
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Producing hydrogen gas. Hence, option D is correct.
What is electrolysis?Electrolysis is described by two half-reactions. These half reaction are the oxidation half-reaction and reduction half-reaction.
Electrolysis involves the transfer of electrons. Each half reaction is characterized by the loss or gain of electrons.
The only reason why producing hydrogen gas is not used most of the time is because electrolysis has very low efficiency, most of the energy finishes up being converted to heat and 95% of the hydrogen is produced by steam reforming.
Hence, option D is correct.
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Comparison between availability of food & population in current scenario.
In UAE.
(10-marks)
100-200 words please
Answer:
Answer is in the attachment
hope it's helpful
11. What is the mass of the object in the picture below? The density is 0.789g/mL.
Hint: You will need to find the volume first!
Answer: 3.156 grams
Explanation: The additional volume is 4 ml. (0.789 g/ml)*(4 ml) = 3.156 grams
How are elements arranged on the periodic table?
a. they are arranged to highlight similarities between elements
b. they are arranged to highlight different elements with similar isotopes
c. they are arranged in order from most abundant to very rare and unstable
d. they are arranged in order of the date of discovery
Answer:
the elements are listed in order of increasing atomic number. The atomic number is the number of protons in the nucleus of an atom.In a periodic table arranged in order of increasing atomic number, elements having similar chemical properties naturally line up in the same column.
The elements on the periodic table are arranged on the basis of highlighting similarities between elements. Thus, the correct option for this question is A.
How elements are arranged on the periodic table?The elements on the periodic table are basically arranged on the basis of increasing their atomic number. These atomic number is represented by the number of protons in the nucleus of an element.
According to the question, the elements possessing identical chemical properties are arranged in the same group. For example, group 17 is known as the halogen group. Among this group, the elements bear one electron short to fulfill their octet.
The whole periodic table comprises of 18 groups and 7 periods.
Therefore, the elements on the periodic table are arranged on the basis of highlighting similarities between elements. Thus, the correct option for this question is A.
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How old is a piece of cotton cloth if the half-life of carbon-14 is 5,730 years, and the carbon-14 composition of the cloth is 22 percent that of living plants?
Answer:5600 years
Explanation:
the amount of time it takes for the quantity to lose 50% (Half life) of its value. The half-life of carbon-14 is about 5600 years. Thus, after 5600 years, a piece of cotton cloth will contain half the carbon-14 that was in the original cotton plant.
electrolysis of aqueous copper(2) sulfate half ionic equation
Answer:
Copper is less reactive than hydrogen, so copper (Cu) is produced at the negative electrode. The half equation is: Cu2+ + 2e- → Cu
The hydroxide ion is more reactive than the sulphate ion, therefore this forms water (H2O) and oxygen at the positive electrode.
What causes the pressure inside oxygen tanks to change as they are filled?
A. The volume of the container changes.
B. The temperature of the gas changes.
C. The number of gas molecules changes.
D. The pressure outside the tanks changes.
Answer:
the answer is the number of gas molecules changes.
How many GRAMS of phosphorus are present in 2.75 moles of phosphorus pentachloride ?
Answer:
molecular weight of Phosphorus Pentachloride or grams The molecular formula for Phosphorus Pentachloride is PCl5. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Phosphorus Pentachloride, or 208.238761 grams.
Explanation:
may this answer is helpful for you
Can someone PLEASE help me with this im struggling bad
Answer:
4.5+2.34= 6.844.5-5 =-0.56.00+3.411= 9.4113.4×2.32 = 7.8887.77/2.3= 3.377. 1200×23.4=28080
9. = 78.512
10. =341.199
11= 7.45
12 =65.0023
13.=3400210.34
Explanation:
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Which statement best describes why an element's atomic number is different from its atomic mass?
A. The atomic number represents the number of electrons, while the atomic mass represents the total mass of the protons and neutrons.
B. The atomic number represents the number of protons, neutrons, and electrons, while the atomic mass represents the total mass of the protons, neutrons, and electrons.
C. The atomic number represents the number of protons, while the atomic mass represents the total mass of the protons, neutrons, and electrons.
D. The atomic number represents the number of protons, while the atomic mass represents the total mass of the protons and electrons.
Answer: C
Explanation: The atomic number is fixed by the number of protons. An element will have an exact number of protons. The neutrons can vary, and they are the reason elements have isotopes (all the same number of protons, but some have differing numbers of neutrons). Electrons are too small to be counted in the atomic weight figures.
How would you calculate the density of an object?
mass/volume
mass * volume
mass/area
weight/mass
Answer:
Mass/Volume
Explanation:
Answer:
[tex]{ \sf{density = \frac{mass}{volume} }}[/tex]
a plant dies if it's phloem tissue is removed .why?
6. When conducting experiments, scientists use
to help guide their processes.
When conducting research, scientists use the scientific method to collect measurable, empirical evidence in an experiment related to a hypothesis (often in the form of an if/then statement), the results aiming to support or contradict a theory.
Hope this helps you!
A gas has a volume of 4.25 m3 at a temperature of 95.0°C and a pressure of 1.05 atm. What temperature will the gas have at a pressure of 1.58 atm and a volume of 2.46 m3
Answer:
[tex]\boxed {\boxed {\sf 82.7 \textdegree C}}[/tex]
Explanation:
We are asked to find the temperature of a gas given a change in pressure and volume. We will use the Combined Gas Law, which combines 3 gas laws: Boyle's, Charles's, and Gay-Lussac's.
[tex]\frac {P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]
Initially, the gas has a pressure of 1.05 atmospheres, a volume of 4.25 cubic meters, and a temperature of 95.0 degrees Celsius.
[tex]\frac {1.05 \ atm * 4.25 \ m^3}{95.0 \textdegree C}= \frac{P_2V_2}{T_2}[/tex]
Then, the pressure increases to 1.58 atmospheres and the volume decreases to 2.46 cubic meters.
[tex]\frac {1.05 \ atm * 4.25 \ m^3}{95.0 \textdegree C}= \frac{1.58 \ atm *2.46 \ m^3}{T_2}[/tex]
We are solving for the new temperature, so we must isolate the variable T₂. Cross multiply. Multiply the first numerator by the second denominator, then multiply the first denominator by the second numerator.
[tex](1.05 \ atm * 4.25 \ m^3) * T_2 = (95.0 \textdegree C)*(1.58 \ atm * 2.46 \ m^3)[/tex]
Now the variable is being multiplied by (1.05 atm * 4.25 m³). The inverse operation of multiplication is division, so we divide both sides by this value.
[tex]\frac {(1.05 \ atm * 4.25 \ m^3) * T_2}{(1.05 \ atm * 4.25 \ m^3)} = \frac{(95.0 \textdegree C)*(1.58 \ atm * 2.46 \ m^3)}{(1.05 \ atm * 4.25 \ m^3)}[/tex]
[tex]T_2=\frac{(95.0 \textdegree C)*(1.58 \ atm * 2.46 \ m^3)}{(1.05 \ atm * 4.25 \ m^3)}[/tex]
The units of atmospheres and cubic meters cancel.
[tex]T_2=\frac{(95.0 \textdegree C)*(1.58* 2.46 )}{(1.05 * 4.25 )}[/tex]
Solve inside the parentheses.
[tex]T_2= \frac{(95.0 \textdegree C)*3.8868}{4.4625}[/tex]
[tex]T_2= \frac{369.246}{4.4625} \textdegree C}[/tex]
[tex]T_2 = 82.74420168 \textdegree C[/tex]
The original values of volume, temperature, and pressure all have 3 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 4 in the hundredth place to the right tells us to leave the 7 in the tenths place.
[tex]T_2 \approx 82.7 \textdegree C[/tex]
The temperature is approximately 82.7 degrees Celsius.
Based on the definition given,
which sentence correctly uses
the word compare?
A. Compare the total amount of rainfall in
California for the year 2011.
B. Compare the similarities of the climate
in Ireland with the climate in Greenland.
C. Compare the best way to prepare to
take a standardized test.
Answer: B. Compare the similarities of the climate in Ireland with the climate in Greenland.
We should Compare the similarities of the climate in Ireland with the climate in Greenland.
What is the equation used to calculate the density of a material?
Answer:
density = (mass) divided by (volume)
or just D = M/V
what is force ?write its effects.
Answer:A force is a push or pull upon an object resulting from the object's interaction with another object.
A force acting on an object causes the object to change its shape or size, to start moving, to stop moving, to accelerate or decelerate
Write the symbol of atoms as per John Dalton.
please tell fast
Answer:
In his 1805 work, "A New System of Chemical Philosophy," Dalton propounded the tenets of his atomic theory: The chemical elements are made of atoms. The atoms of an element are identical in mass. Atoms of different elements have different masses.
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Calculate the moles in 3x10^22molecules of water
Answer:
It is 0.05 moles of water
Explanation:
From avogadro's number:
[tex]{ \sf{6.02 \times {10}^{23} \: mole cules= 1 \: mole }} \\ { \sf{3 \times {10}^{22} \: molecules = ( \frac{3 \times {10}^{22} }{6.02 \times {10}^{23} }) \: moles }} \\ \\ { \sf{ = 0.05 \: moles}}[/tex]
Answer:
[tex]\boxed {\boxed {\sf 0.05 \ mol \ H_2O}}[/tex]
Explanation:
We are asked to calculate the number of moles of water, given the molecules of water.
We will convert moles to molecules using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are molecules of water or H₂O.
We will convert using dimensional analysis, so we must set up a ratio using Avogadro's Number.
[tex]\frac {6.022 \times 10^{23} \ molecules \ H_2O} { 1 \ mol \ H_2O}[/tex]
We are converting 3 × 10²² molecules of water to moles, so we must multiply the ratio by this value.
[tex]3 \times 10^{22} \ molecules \ H_2O*\frac {6.022 \times 10^{23} \ molecules \ H_2O} { 1 \ mol \ H_2O}[/tex]
Flip the ratio so the units of molecules of water cancel.
[tex]3 \times 10^{22} \ molecules \ H_2O*\frac{ 1 \ mol \ H_2O} {6.022 \times 10^{23} \ molecules \ H_2O}[/tex]
[tex]3 \times 10^{22} *\frac{ 1 \ mol \ H_2O} {6.022 \times 10^{23}}[/tex]
[tex]\frac {3 \times 10^{22}} {6.022 \times 10^{23}} \ mol \ H_2O[/tex]
[tex]0.04981733643 \ mol \ H_2O[/tex]
The original value of molecules of water ( 3 × 10²² ) has 1 significant figure, so our answer must have the same number of sig figs. For our answer that is the hundredth place. The 9 in the thousandth place tells us to round the 4 in the hundredth place up to a 5.
[tex]0.05 \ mol \ H_2O[/tex]
3×10²² molecules of water are equal to 0.05 moles of water.
The density of a substance is 1.63 grams per milliliter. What is the mass of 0.25 liters of the substance in grams?
Answer:
407.5 g
Explanation:
Hope it helps.
what are adipoyl chloride used for or uses?
Answer:
Explanation:
It is a colorless liquid. It reacts with water to give adipic acid. It is prepared by treatment of adipic acid with thionyl chloride.
Adipoyl Chloride can be used in the synthesis of nylon. Also it is used in the synthesis of chiral polymer for membrane application.
1 Write the correct symbol, with both superscript and subscript,
for each of the following. Use the list of elements in the front
inside cover as needed: (a) the isotope of platinum that contains
118 neutrons, (b) the isotope of krypton with mass number 84,
(c) the isotope of arsenic with mass number 75, (d) the isotope of
magnesium that has an equal number of protons and neutrons.
Answer:
+27 66 514 3800
Explanation:
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Evaporation of water off of the surface of leaves
a
Chemical Change
b
Physical Change
20 point for right answer
Answer:The below file contains the answer
Explanation:
Write an ionic equation for oxygen reacting with water to form hydroxide ions at the cathode
Explanation:
oxygen (O)will react with water(H2O) to form hydroxide which is (OH