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You need to find the entropy of fusion in order to find this out.

Answer:

Detail is given below.

Explanation:

Calcium is alkaline earth metal. It has two valance electron. Thus calcium needs six more electron to complete the octet. Thus, its very easy for calcium to remove its two electron and get complete octet.

Electronic configuration of Ca:

Ca₂₀ = [Ar] 4s²

While,

Fluorine is halogen. It has seven valance electrons. It needed only one electron to complete the octet. When it combine with calcium , calcium loses two electrons thus two atom of fluorine combine with one atom of fluorine and stable compound calcium fluoride is formed.

Electronic configuration of F:

F₉  = [He] 2s² 2p⁵

Chemical equation:

Ca  + F₂     →     CaF₂

Answer:

To encourage readers to vary the design

Explanation:

Answer:

An ionic charge of 2-

Explanation:

The number of electrons is 8 and the number of protons is 2, subtract the two and the difference is the ionic charge. Hope this helps! :)

Answer:

This answer would be 2

Explanation:

The way that I have always done it is you put protons in tally marks (without crossing) over the top of the neutrons and mark them out one by one and whichever one that you have leftover that is your charge.

Hope this helps!

Answer:

The penny now weighs 0.0025kg

Hope this helps please give me brainliest!

God bless!

Answer:

why do you not ask to your maam the answer

Answer:

After 7.648 days, you will see one quarter.

Explanation:

1 → 0.5 → 0.25

Since half life of radon-222 is 3.824 days, you need twice this time to get one quarter at the end.

2 ⋅ 3.824 = 7.648 days.

Answer:

22572J

Explanation:

a) The following values have been given:

Mass of water = 180.0g

Initial temperature = 10°C

Final temperature = 40°C

molar heat capacity for water = 75.3J/Kmol

To calculate the specific heat capacity of water (c), we divide the molar heat capacity by molar mass of water (18g/mol)

That is; 75.3/18

= 4.183 Jg/K

b) The enthalpy change denoted by ∆H is the value we are trying to find.

c) To find enthalpy change (∆H), we use the formula:

∆H = m × c × ∆T

Where; m= mass

c= specific heat capacity

∆T= change in temperature =

(final temp - initial temp)

∆H = m × c × ∆T

∆H = 180 × 4.18 × (40-10)

∆H = 180 × 4.18 × 30

∆H = 22572J

Answer:

an endothermic reaction

Explanation:

An endothermic reaction has occurred.

Answer:

endothermic

Explanation:

took the quiz

Answer:

Explanation:

Density is m/V. Also, 1 liter = 1000 [tex]cm^3[/tex]. So, we get 0.890/(5*1000) = [tex]1.78*10^{-4}[/tex] g/cm^3. You can convert this to kg/m^3 as well by multiplying it by 10. Depends which one you want.

The ratio of the mass in grams and volume in cubic meters gives the density. The density of 0.80 gm helium is 1.78 × 10 ⁻⁴ g/cm³.

Density is the amount or the number of entities that can be contained in an area. It is denoted by ρ and is calculated as,

Given,

Mass = 0.890 gm

Volume = 5000 cm³

ρ = Mass ÷ Volume

= 0.890 ÷ 5000

= 1.78 × 10 ⁻⁴ g/cm³

Therefore, 1.78 × 10 ⁻⁴ g/cm³ is the density of helium.

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Answer:

A) one electron in each orbital

Explanation:

Orbitals get electrons one at a time. If there are three electrons and three empty orbitals, then one electron will go into one orbital!

Answer:

Excited state of an electron is the state attained by an electron after it has absorbed energy and it moves further from the nucleus.

an electron is at higher energy when excited and at lower energy when at ground state.

an excited electron is less stable due to the decrease in the nuclear force of attraction and the grounded electron is more stable due to it's close distance to the nucleus.

An electron in excited state has its electron present in higher energy level while an electron in ground state is present in lower energy level.

Electrons present in an atom revolve in different orbits which are stationary states and are also called as energy levels. The energy levels are numbered as integers which are also called as principal quantum numbers.

Energy of the stationary state is given as E= -R

1/n² where R

is the Rydberg's constant. When an electron is excited, and it moves from lower to higher energy levels there is absorption of energy, while when it moves from higher energy level to lower energy level it radiates or gives out energy in the form of radiation.

They can also be defined as the distances between electron and nucleus of an atom . Electrons present in K energy level have least energy .Energy level diagrams are studied to understand nature of bonding , placement of electrons in orbits and and elemental behavior under certain conditions.

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Answer:

C 14

Explanation:

Silicon atom has 14 protons. Given that a positive and a negative neutralize each other you need 14 electrons to neutralize the 14 protons.

Answer:

Sulfur

Explanation:

The Answer fam is......... 1.82 × 10^4, Hence It's B)

Answer:

false

Explanation:

the energy causes the bonds to become looser

Answer:

Earth is pulling up on the book with a force of 4n i think

Explanation:

Answer:

Explanation:

This should be in physics.

d = 100 meters south

t = 13 seconds

v = d/t

v = 100 / 13

v = 7.69 m/s going south.

The point is that you have to specify the direction.

Answer:

Br.

neutron = mass number - atomic number

youcan see the answer at the pic

The isotope that has 45 neutrons is B. 80,35Br.

The neutron can be obtained by subtracting the protons from the mass number. In the question, we have a proton that is numbered, 35 and a mass number of 80.

So, to get the neutron, we would subtract the protons from the mass number as follows;

80 - 35 = 45. The element that is described by this data is Bromine. Therefore, the correct option number is B. 80,35Br.

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Answer:

you shoudl ask this question more clearly?

Explanation:

Answer:

The 20th Element is Calcium (Ca).

The 20 Elements are:

Hydrogen

helium

lithium

berilium

boron

carbon

nitrogen

oxygen

flourine

neon

sodium

magnesium

aluminium

silicon

phosphorus

sulphur

chlorine

argon

potassium

calcium

Answer:

162.7miles/hr

Explanation:

Given parameters:

Distance covered by the train  = 813.5miles

Time taken  = 5hours

Unknown:

Speed of the train  = ?

Solution:

Speed is a physical quantity.

It is mathematically expressed as;

      Speed  = [tex]\frac{distance}{time}[/tex]

So, input parameters and solve;

   Speed  = [tex]\frac{813.5}{5}[/tex]  = 162.7miles/hr

Answer: Ionic

Explanation:

Answer:

ionic

Explanation:

Answer:

mass number

Explanation:

When there is an element name followed by a dash and then a number, the number simply represents the mass number.

for example:

Oxygen- 18

18 represents the mass number of this particular isotope

Answer:

See explanation

Explanation:

This question is obviously supposed to be a multiple choice question but the options are missing.

However, the question intends to test the student's knowledge about combustion of fossil fuels. Fossil fuels are mostly composed of hydrocarbons of different chain lengths.

The longer the chain length, the greater the energy released when the compound is burnt since there are more energy stored in its bonds.

Hence, the correct answer to this question will be the option that contains the greatest number of C-C and C-H bonds.

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question

mass = 4 g

volume = 2 cm³

We have

[tex]density = \frac{4}{2} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

D = 2 g/cm³

Explanation:

Density = mass over volume

D= m/v

Step 1: Define

m= 4 grams

v= 2 cm³

Step 2: Substitute and Evaluate

D= 4 g/2 cm³

D= 2 g/cm³

The specific heat  capacity of the metal : 0.610 J/g° C  

The law of conservation of energy can be applied to heat changes, i.e. the heat received/absorbed is the same as the heat released  

Q abs = Q received  

Heat can be calculated using the formula:  

Q = mc∆T  

Q = heat, J  

m = mass, g  

c = specific heat, joules / g ° C  

∆T = temperature difference, ° C / K  

∆T = T(final temp) - T(initial temp)

mass of metal = 38 g

T initial metal = 92 °C

mass of water = 43 g

T final water = 30  °C

T initial water = 22°C

c water = 4.18 J/g° C  

[tex]\tt Q=m.c.\Delta T\\\\Q=43\times 4.18\times (30-22^oC)\\\\Q=1437.92~J[/tex]

Q water = Q metal

[tex]\tt 1437.92=38\times c\times (92-30)\\\\c=0.610~J/g^oC[/tex]

Answer:

a particle

Explanation:

matter takes up space, and particles take place in atoms

Answer:

plasma is a state of matter

Answer:

Molar mass of gas = 160 g/mol

Explanation:

Given data:

Mass of sample gas = 1.28 g

Temperature of sample gas = 127°C (127+273 = 400K)

Pressure of sample gas = 1 atm

Volume of sample gas = 0.250 L

Molar mass of gas = ?

Solution:

Formula:

PV = nRT

R = general gas constant = 0.0821 atm.L/ mol.K

Now we will put the values in formula.

1 atm × 0.250 L = n × 0.0821 atm.L/ mol.K ×400K

0.250 L.atm   = n ×32.84atm.L/ mol

n = 0.250 L.atm/32.84atm.L/ mol

n = 0.008 mol

Molar mass of gas:

Number of moles = Mass/molar mass

0.008 mol = 1.28 g / molar mass

Molar mass = 1.28 g / 0.008 mol

Molar mass = 160 g/mol