the atomic number of calcium is 20 . the maximum possible numbers of electron in m-shell is a 2 b 8 c 18 d 10​

Answer:

The unstable nucleus of radioactive atoms emit radiation.

Explanation:

When the atoms of an element have extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced and unstable, or radioactive.

(https://www.epa.gov/radtown/radtown-radioactive-atom-activity-4-atomic-stability)

Answer:

When the atoms of an element have extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable. Whether radioactive elements can become stable and if so, how. The unstable nucleus of radioactive atoms emit radiation. ... This process is called radioactive decay.

Explanation:

Answer:

For the equilibrium reaction 2HBr(g)⇌H

2

(g)+Br

2

(g) , the equilibrium constant is K=

1.6×10

5

1

.

Let the decease in the equilibrium pressure of HBr be p bar.

The initial pressures of HBr, H

2

,Br

2

are 10 bar, 0 bar and 0 bar respectively.

The equilibrium pressures are 10-p, p/2 and p/2 respectively.

The equilibrium constant expression is

K

p

=

(P

HBr

)

2

P

H

2

P

Br

2

=

(10−p)

2

(p/2)×(p/2)

=

1.6×10

5

1

4(10−p)

2

p

2

=

1.6×10

5

1

400p=20−2p

p=0.0498 bar

The equilibium pressures are

P

H

2

=P

Br

2

=

2

0.0498

=0.0249 bar

P

HBr

=10−0.0498=10 bar

Explanation:

Answer:

Option 2 variable

Explanation:

Answer:

variable.

Explanation:

A variable is anything that can change or be changed. In other words, it is any factor that can be manipulated, controlled for, or measured in an experiment.

Answer: B. An experiment that directly tests the hypothesis

Explanation:

Yasir didn’t really test his experiment he only ask people for the opinion on which color they like so he forget to actually do the experiment therefore the answer is b.

Answer:

B. an experiment that directly tests the hypothesis

Explanation:

this was on my test i got it right

Answer:

(a).

[tex]{ \sf{1000 \: {cm}^{3} \: contains \: 0.2 \: moles \: of \: acid}} \\ { \sf{25 \: {cm}^{3} \: contains \: ( \frac{25 \times 0.2}{1000} ) \: moles}} \\ \\ = { \sf{0.005 \: moles}}[/tex]

» 0.005 moles of sulphuric acid are present.

(b).

from the equation:

[ 1 mole of acid reacts with 2 moles of sodium hydroxide ]

[tex]{ \sf{1 \: mole \: of \: acid \: reacts \: with \: 2 \: moles \: of \: hydroxide}} \\ { \sf{0.005 \: moles \: of \: acid \: react \: with \: (0.005 \times 2) \: moles}} \\ { \sf{ = 0.01 \: moles}}[/tex]

» 0.01 moles of sodium hydroxide reacted.

(c).

[tex]{ \sf{10 \: {cm}^{3} \: contains \: 0.01 \: moles \: of \: hydroxide }} \\ { \sf{1000 \: {cm}^{ 3} \: contain \: ( \frac{1000 \times 0.01}{10} ) \: moles}} \\ \\ { \sf{ = 1 \: mol \: {l}^{ - 1} }}[/tex]

» concentration is 1 M

Explanation:

Hope it helps.

Thank you

The statement about pure substances and elements  correct is all elements are pure substances ,therefore option (b) is correct .

An element is a pure substance whose atoms all have the same number of protons.

Elements are the simplest chemical elements and thus can not be broken down through chemical reactions.

Characteristics of element -:

The statement about pure substances and elements  correct is all elements are pure substances ,therefore option (b) is correct .

Learn more about elements ,here :

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Answer:

Loading...

Explanation:

[tex]\\ \sf\longmapsto FeP[/tex]

[tex]\\ \sf\longmapsto Fe_2S_3[/tex]

[tex]\\ \sf\longmapsto FeCl_2[/tex]

[tex]\\ \sf\longmapsto MgCl_2[/tex]

[tex]\\ \sf\longmapsto MgO[/tex]

[tex]\\ \sf\longmapsto Mg_3N_2[/tex]

[tex]\\ \sf\longmapsto Na_3P[/tex]

[tex]\\ \sf\longmapsto Na_2S[/tex]

[tex]\\ \sf\longmapsto CoO[/tex]

[tex]\\ \sf\longmapsto Co_2S_3[/tex]

[tex]\\ \sf\longmapsto AlCl_3[/tex]

[tex]\\ \sf\longmapsto CsBr[/tex]

[tex]\\ \sf\longmapsto Ti_2O_4[/tex]

[tex]\\ \sf\longmapsto Ag_2S[/tex]

The correct answer is: it is a chemical change, which could change some of the intensive and extensive properties of the carbon.

To answer this question, we must bear in mind that a chemical change involves the breaking of bonds in a substance and subsequent rearrangement of atoms to form a new substance.

This is why we say that in a chemical change, new substances are formed. Another name for a chemical change is a chemical reaction.

Having said that, it is clear that as graphite changes to diamond, bonds are broken and carbon atoms are rearranged.

This rearrangement of atoms leads to different intensive and extensive properties for graphite and diamond. For instance, graphite conducts electricity but diamond does not conduct electricity. Also, diamond is much denser and harder than graphite. A physical change can not lead to change in  some of the intensive and extensive properties of the carbon.

Learn more:https://brainly.com/question/8853712

Lets find

[tex]\\ \sf\longmapsto H_2SO_4[/tex]

[tex]\\ \sf\longmapsto 2(1u)+32u+4(16u)[/tex]

[tex]\\ \sf\longmapsto 2u+32u+64u[/tex]

[tex]\\ \sf\longmapsto 34u+64u[/tex]

[tex]\\ \sf\longmapsto 98u[/tex]

Answer:

Relative dating is based on the positions of fossils in rock layers. Lower layers were laid down earlier, so they are assumed to contain older fossils. This gives the fossil an approximate age in years. Absolute dating is often based on the amount of carbon-14 or other radioactive element that remains in a fossil up until extinction.

Relative dating is a method of dating where the geologic events are arranged and the rocks are left behind in a sequence. They function on the basis of the stratigraphy and don't provide us with actual numeric data.

Learn more about the discoveries to explain how the fossil record.

brainly.com/question/22311467.

Explanation:

Metallic bond, force that holds atoms together in a metallic substance

Answer:

[tex]\boxed {\boxed {\sf 4 \ g/cm^3}}[/tex]

Explanation:

We are asked to find the density of a brick. Density is a substance's mass per unit volume. The formula for calculating density is as follows.

[tex]\rho= \frac{m}{v}[/tex]

The mass of the brick is 100 grams and the volume is 25 cubic centimeters.

Substitute the values into the formula.

[tex]\rho= \frac{ 100 \ g}{25 \ cm^3}[/tex]

Divide.

[tex]\rho=4 \ g/cm^3[/tex]

The density of the brick is 4 grams per cubic centimeter.

Answer:

cell

tissue

organ

organ system

Explanation:

the cell is the smallest

a tissue looks like a unit

an organ is multiple units

organ systems are the full body

No.

The smallest quantity is 600 centiliter and the largest is 600 kiloliter.

Answer:

865 kg/m³; 0865 g/cm³

Explanation:

Answer:

4.  0.5 kilometers (1st option)

5.  0.1 00 liters (last option)

Explanation:

500 meters to kilometers

4.

1 kilometer = 1000 meters

We use the formula SBD (SMALL TO BIG DIVIDE) i hope this helps you

500 ÷ 1000

= 0.5 kilometers

5.

100 milliliter to liter

SBD

100 ÷ 1000

= 0.1 00 liters

Answer:

Experience in star is very nice

Explanation:

Because i love stars

Answer:

B

Carboxylic acid

Explanation:

I'm not entirely sure, but this should be it

Answer:

25,98 amu and 11.01% abundance

Explanation:

1. Find the missing abundance

100 - 78.99 - 10 = 11.01 %

2. Using each mass and abundance and the periodic table for the Mg amu

And let Isotope = Mg

23.9850(78.99%) + 24.9858(10%) + Mg(11.01%) = 24.305 (100%)

Solve for Mg

Mg = 25,98

Answer:

2,405 g

Explanation:

[tex]nH^{+}[/tex] = 0,1 x 0,3 = 0,03 mol

Do dung dịch axit có nồng độ bằng nhau nên sô mol bằng nhau

⇒ n HCl = n HBr = n HNO3 = [tex]\frac{0,03}{3}[/tex] = 0,01

Do trung hào dung dịch axit nên n [tex]H^{+} = n OH^{-}[/tex] = 0,03

m Muối = m Axit + m Bazơ - m[tex]H_{2} O[/tex]

            = 0,01 ( 36,5 + 81 + 63 )  + 1,14 - 0,03 x 18 = 2,405g

Answer:

The radius of a calcium atom would be larger than that of a magnesium atom.

The radius of a calcium atom would be slightly smaller than that of a potassium atom.

Explanation:

Refer to a modern copy of the periodic table.

Calcium and magnesium are in the same column. They are in the same group (IUPAC group [tex]2[/tex].)

Hence, atoms of calcium and magnesium would have similar effective nuclear charges. In other words, the attraction between a calcium atom nucleus and its valence electrons would be similar to that of magnesium.

However, calcium is in the fourth row of the periodic table (fourth period) while magnesium is in the third (third period.) A calcium atom would thus have four main shells with electrons. In contrast, a magnesium atom would only have three such main shells.

Despite the similar effective nuclear charge (effective attraction on the outermost electrons,) the radius of a calcium atom would be larger than that of a magnesium atom because of the extra main electron shell.

On the other hand, calcium and potassium are in the same row (same period.) A calcium atom and a potassium atom would both include four electron-filled main shells.

However, with one additional proton per atom, the effective nuclear charge of calcium atoms would be greater than that of potassium atoms. Hence, when compared to potassium nuclei, the nucleus of a calcium atom would pull its electron shells closer to the center. The radius of a calcium atom would thus be smaller than that of a potassium atom.

In general, atomic radius would generally become larger when moving down a column in the periodic table. On the other hand, atomic radius would general become smaller when moving towards the right-hand side of a row in the periodic table.

The most abundant isotope is Gz-83 because the average atomic mass of Gz is closer to 83.

The average atomic mass is defined as the weigthed mean of the isotopes.

The mass of the isotopes is 80, 81 and 83 uma, respectively.

As the average atomic mass (82.74uma) is closer to the atomic mass of Gz-83 than the mass of the other isotopes, you can interpretate that the most abundant isotope is Gz-83.

Learn more about average atomic mass in:

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Explanation:

I think it is d because it is a gas

Answer:

The flame colour of potassium is Lilac

THANKS

Answer:

(ethanol) into acetic acid or vinegar. When wine is exposed to the air, Oxygen in the air interacts with the wine. The wine changes colour and turns both white and red wines brown.

Explanation:

Answer:

[tex]oxygen \: at \: 94.1\% \: hydrogen \: at \: 5.9\% \\ at \: 100gram \: oxygen \: \\ \: 94.1\% = .941 \times 100g \\ = 94.1 \times \frac{1mol}{16g} = 5.88g \\ hydrogen \: \\ 5.9\% = .059 \times 100 = 5.9 \times \frac{1mol}{1.002g} = 5.88g \\ here \: oxygen = hydrogen \: so \: ratio \\ = 1 \: \: \: 1 \: \\ emperical \: formula \: = oh\\ thank \: you[/tex]

Composition:

5.9% Hydrogen and 94.1% Oxygen (by mass)

in a 100 gram sample:

5.9 gram Hydrogen

94.1 gram Oxygen

Finding the number of moles:

Moles of Hydrogen:

moles = given mass/ molar mass

moles = 5.9 / 1          [molar mass of Hydrogen = 1g/mol]

moles of hydrogen = 5.9 moles

Moles of Oxygen:

number of moles = given mass / molar mass

number of moles  = 94.1 / 16          [molar mass of Oxygen = 16g/mol]

moles of Oxygen = 5.88 ≈ 5.9 moles

Empirical Formula:

Moles of Hydrogen : Moles of Oxygen

5.9 : 5.9

Moles of Hydrogen : Moles of Oxygen = 1:1

Empirical Formula = OH