An atom of beryllium has 4 protons, 4 electrons, and 5 neutrons. What is its mass number?

Answer:

Physical models can represent objects or systems that are too small, too big, or too far away to study. They are way easier, cheaper, and safer to work with or use when compared to the real objects that they represent.

Explanation:

Answer:

FALSE.

Explanation:

The right answer is false. There are three different groups of phylum for worms.

Hope this helped!

Answer:

FALSE

there are like 3 different phylum

Explanation:

Hope this helps!

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please mark Brainlist!!

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Answer:

2.51x10⁻⁵ mmol MgF2/L

Explanation:

To find the concentration in mmol / L we need to convert μmol to mmol (1000μmol / 1mmol) and mL to Liters (1000mL / 1L) as follows:

μmol MgF2:

0.0113μmol MgF2 * (1mmol / 1000μmol) = 1.13x10⁻⁵ mmol MgF2

Liters solution:

450mL * (1L / 1000mL) = 0.450L

Concentration in mmol/L:

1.13x10⁻⁵ mmol MgF2 / 0.450L =

Answer:

Electron cloud

Explanation:

If you were to scale the size of the atom up to have the nucleus be about the size of a basket ball, then the placement of the actual electrons (about the size of a large marble at this scale) throughout the cloud would be many yards away from the nucleus.

Answer:

273.9m/s

Explanation:

Given parameter:

Kinetic energy of the ball  = 4.5kJ

Mass of the ball  = 120g

Unknown:

Speed of the ball  = ?

Solution:

Kinetic energy of a body is the energy due to the motion of a body.

 K.E  = [tex]\frac{1}{2}[/tex] m v²

where m is the mass

           v is the speed

Convert the quantities to the appropriate units;

     4.5kJ to J  = 4.5 x 10³J

 120g to kg  = 0.12kg

Now insert the parameters and find the unknown:

       4500  = [tex]\frac{1}{2}[/tex] x 0.12 x V²  

      9000 = 0.12V²  

       V²  = [tex]\frac{9000}{0.12}[/tex]   = 75000

        V  = 273.9m/s

Explanation:

Just like an independent variable, a dependent variable is exactly what it sounds like. It is something that depends on other factors. For example, a test score could be a dependent variable because it could change depending on several factors such as how much you studied, how much sleep you got the night before you took the test, or even how hungry you were when you took it. Usually when you are looking for a relationship between two things you are trying to find out what makes the dependent variable change the way it does.

Answer: 1M

Explanation:

Molarity = mols/L

moles of lead bromide: 183.51/ 367.0 = 0.5 mol

500 ml/ 1000 mL = .5L

.5 mol / .5 L = 1 mol/L = 1M

Answer: increase number of collisions

Explanation:

Decreasing the volume increases the likelihood of particles interacting more often.

Answer:

Atoms collided more often when the volume was lower.

Explanation:

plato

The energy produced in the burning of gasoline = 45 kJ/g. So, amount of energy produced by burning 48 L gasoline = 45 kJ/g×36960 g = 1663200 kJ.

Answer:

a) O2, Pt, Rh

b) Rb, Y, Sm, Mn, Sn, Li

c)Rb

Explanation:

We must consider the reduction potentials of each of the species in the question.

In (a) above, all the elements whose reduction potential is higher than the redox potential for the oxidation of I^- will react with a solution of I^- to generate I2 as shown above.

In (b) above, all the strong reducing agents can donate electrons to Ag^+ and reduce it to Ag as shown above.

In (c) Rb has a more negative reduction potential than sodium hence it can react with a solution of sodium salt to generate sodium metal.

Answer:

In 1924, the French physicist, Louis de Broglie suggested that if light has electron, behaves both as a material particle and as a wave. According to this theory, small particles like electrons when in motion possess wave properties.

Explanation:

examples

This can be derived as follows according to Planck’s equation, E = hv = hc /λ ∴ v=c/λ(energy of the photon (on the basis of Einstein’s mass energy relationship) E = mc2    

( If Bohr’s theory is associated with de-Broglie’s equation then wave length of an electron can be determined in bohr’s orbit and relate it with circumference and multiply with a whole number 2πr = nλ or λ = (2πr/2π) From de-Broglie equation, λ = (h/mv).  

Answer:

3,686,400,000 Joules

Explanation:

Energy = 1024 kWh

To be converted to Joules.

The relationship between kwh and joules is;

1 kilowatt-hour = 3600000 J

So we have;

1 = 3600000

1024 = x

x = 1024 * 3600000

x = 3,686,400,000 Joules

Answer:

Explanation:

C = 49.48

H = 5.19

O = 16.48

N = 28.85

ratio of moles

= 49.48 / 12 : 5.19 / 1 : 16.48 / 16 : 28.85 / 14

= 4.123 : 5.19 : 1.03 : 2.06

= 4 : 5 : 1 : 2

so the empirical formula = C₄ H₅O N₂

Let molecular formula = (  C₄ H₅ON₂ )ₙ ,

n ( 48 + 5 + 16 + 28 ) = 119.19

97 n = 194.19

n = 2 ( approx )

molecular formula = C₈ H₁₀O₂ N₄

Answer:

is c a mixture of minerals

Explanation:

Answer:

6.05%

Explanation:

From the question given above, the following data were obtained:

Decay constant (K) = 0.0561 /yr

Time (t) = 50 years

We can obtain the percentage of tritium remaining after 50 years by using the following formula:

Log (N₀/N) = kt /2.303

NOTE:

N₀ is the original amount.

N is the amount remaining.

K is the decay constant.

t is the time

Log (N₀/N) = (0.0561 × 50) /2.303

Log (N₀/N) = 2.805/2.303

Log (N₀/N) = 1.218

Take the anti log of 1.218

(N₀/N) = anti log (1.218)

(N₀/N) = 1.218

N₀/N = 16.52

Invert and multiply by 100 to obtain the percentage.

N/N₀ = 1/16.52 × 100

N/N₀ = 6.05%

Thus, the percentage of tritium remaining after 50 years is 6.05%

Answer:

6.08% remains after 50 years

Explanation:

The radioactive decay follows the equation:

Ln[A] = -kt + Ln [A]₀

Where [A] is concentration of reactant after time t, [A]₀ is its initial concentration, k is rate constant and t is time.

Assuming its Initial concentration is 100%

Time is 50 yr

k is 0.056 yr⁻¹

And [A] is our incognite

Ln[A] = -0.056 yr⁻¹*50yr + Ln [100%]

ln[A] = 1.805

[A] =

Answer:

The answer is the second one

Answer:

100% sure about that....just believe me

Hope u the best and hope that helps

Answer:

residue is whatever remains after something else has been removed while filtrate is the liquid or solution that has passed through a filter, and which has been separated from the filtride.

filtration id done by placing a filter paper on the beaker or container then pour the filtride then let it settle and it will pass through and you will have the fitrate and residue

Explanation:

Answer:

Kinetic energy

Explanation:

Fireworks convert chemical energy into kinetic energy to send them flying upward. Hope it is correct!

Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart.

Answer:

Ne is the identity of the gas

Answer:

mass in gram = 642.6 g

Explanation:

Given data:

Density of aluminum = 2.70 g/mL

Volume of aluminum = 238 mL

Mass in gram = ?

Solution:

Density:

Density is equal to the mass of substance divided by its volume.  The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

d =m/v

d = density

m=mass

V=volume

Now we will put the values in formula.

2.70 g/mL = m/ 238 mL

m = 2.70 g/mL × 238 mL

m = 642.6 g

Answer: A LOWER ENERGY

Explanation:

did the test

Answer:

A lower energy!

Explanation:

I know this is not much of an explanation but I took the test i hope you have an amazing day afternoon or night! Hope this helps :3

Answer:

C. The weaker the acid, the higher the pH at the equivalence point.

Explanation:

In a titration, a solution which concentration is known is added gradually to another solution of unknown concentration, until the chemical reaction between the two solutions is complete.

The pH in the equivalence point is equal to 7.00 only if both the acid and base are strong. When one or both reactants are weak, the pH in the equivalence point is not equal to 7.00.

In the equivalence point, the amount of strong base (like NaOH) added is just enough to react stoichiometrically with the weak acid. The resulting solution "only" contains the conjugated base A⁻. A solution of Na⁺A⁻ is the solution of a weak base:

A⁻ + H₂O ⇄ HA + OH⁻              Kb=Kw/Ka

In the equivalence point of the titration of a weak base with a strong base, the pH is higher than 7.00 because at this point the acid is transformed into its conjugate base.

Answer: A

Explanation:

Metalloids

Answer:

coke and mentos are basically just a small scale replica

Explanation:

Answer:

Tollen's test or silver mirror test is use to distinguish between ketone and aldehyde.

Explanation:

Tollen's test is use to distinguish aldehyde from ketone because Tollen reagent consist of silver nitrate and ammonia and it oxidized aldehydes to carboxylic acid and the silver Ag+ is reduced to solid silver Ag. It form a inner film wall on the tube that look like mirror. Ketone do not react with Tollen reagent and therefore does not form silver mirror on the tube wall.

Answer:

0.19 mol H₂O

General Formulas and Concepts:

Chem

Explanation:

Step 1: Define

Given: 3.5 g H₂O from RxN

Step 2: Define conversions

Molar Mass of H - 1.01 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H₂O - 2(1.01) + 16.00 = 18.02 g/mol

Step 3: Convert

[tex]3.5 \ g \ H_2O(\frac{1 \ mol \ H_2O}{18.02 \ g \ H_2O} )[/tex] = 0.194229 mol H₂O

Step 4: Check

We are given 2 sig figs. Follow sig fig rules.

0.194229 mol H₂O ≈ 0.19 mol H₂O