Please help me, Thank you!

Answer:

The stability of atoms depends on whether or not their outer-most shell is filled with electrons. If the outer shell is filled, the atom is stable. Atoms with unfilled outer shells are unstable, and will usually form chemical bonds with other atoms to achieve stability.

Explanation:

Answer:

The stability of atoms depends on whether or not their outer-most shell is filled with electrons. If the outer shell is filled, the atom is stable. Atoms with unfilled outer shells are unstable, and will usually form chemical bonds with other atoms to achieve stability.

Explanation:

Answer:

the discovery of atomic structure.

Explanation:

Rutherford was a famous scientist who gave his theory of atomic structure.

Ernest Rutherford was a great physicist who is well known for his pioneering studies and discoveries about atoms and radioactivity. Rutherford was considered to be the greatest experimentalist after Michael Faraday.

Rutherford's atomic model was one of the greatest discoveries which provided many answers and solutions to the structure of atom and molecules that our earth is surrounded of.

Rutheford discovered that an atom has a tiny mass of positively charged particles in the centre of the atom called nucleus and negatively charged electrons surrounds the nucleus.

Bohr joined Rutherford in his studies and discovered many new facts about the structure of the atom based on the Rutherford's model. Today atomic model is the product of Rutherford atomic structure.

Answer:

metal is heavier than wood.

Explanation:

metal is made of rock which doesn't have air in it while wood has air in it making it lighter

pH of solution = 13.033

Given

2.31 g Ba(OH)₂

250 ml water

Required

pH of solution

Solution

Barium hydroxide is fully ionized, means that Ba(OH)₂ is a strong base

So we use a strong base formula to find the pH

[OH ⁻] = b. Mb where

b = number of OH⁻ /base valence

Mb = strong base concentration

Molarity of Ba(OH)₂(MW=171.34 g/mol) :

[tex]\tt M=\dfrac{mol}{L}=\dfrac{2.31~g\div 171.34~g/mol}{0.25~L}\\\\M=0.054[/tex]

Ba(OH)₂ ⇒ Ba²⁺ + 2OH⁻(b=valence=2)

[OH⁻]= 2 . 0.054

[OH⁻] = 0.108

pOH= - log 0.108

pOH=0.967

pOH+pH=14

pH=14-0.967

pH=13.033

Answer:

The displacement is 0.05 meters. The angle between the upward force and the upward displacement is 0 degrees. The work for 1 push-up is approximately. W = 10 N * 0.05 m * cos 0 degrees = 0.5 Joules. If the squirrel does a total of 5.0 Joules of work, then it must have done about 10 push-ups.

Explanation:

Answer:

The answer is A.

Explanation:

The answer is A because it is talking about a living organism.

Hope this helps! :)

Answer:

Explanation:

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

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

From the question we have

[tex]density = \frac{402}{384} \\ = 1.046875[/tex]

We have the final answer as

Hope this helps you

Answer: St Br2

Explanation: Br has only one valence electrons and Sr has 2 valence electrons this is why we need 2 atoms of Br to for an ionic compound with 1 atom of Sr.

Answer:

B

Explanation:

Just took the test

Answer:

b

Explanation:

edge 2021

Answer:

(a)

[tex]v = 10.1mL[/tex] --- Silicon

[tex]v = 9.0mL[/tex] --- Tin

[tex]v = 7.5mL[/tex] -- Lead

(b)

[tex]d = 1.55g/mL[/tex] --- Silicon

[tex]d = 5.56g/mL[/tex] --- Tin

[tex]d = 9.53g/mL[/tex] --- Lead

Explanation:

Given

The attached table

Solving (a): The volume of each sample

For each element, the volume (v) is calculated as:

[tex]v = v_f - v_i[/tex]

Where:

[tex]v_f = Final\ Volume[/tex]

[tex]v_i = Initial\ Volume[/tex]

So, we have:

Silicon:

[tex]v_f = 40.1mL;\ \ \ v_i = 30.0mL[/tex]

So, we have:

[tex]v = 40.1mL - 30.0mL[/tex]

[tex]v = 10.1mL[/tex]

Tin:

[tex]v_f = 29.0mL;\ \ \ v_i = 20.0mL[/tex]

So, we have:

[tex]v = 29.0mL - 20.0mL[/tex]

[tex]v = 9.0mL[/tex]

Lead:

[tex]v_f = 33.5mL;\ \ \ v_i = 26.0mL[/tex]

So, we have:

[tex]v = 33.5mL - 26.0mL[/tex]

[tex]v = 7.5mL[/tex]

Solving (b): The density of each sample

For each element, the density (d) is calculated as:

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

Where

[tex]m = mass[/tex]

[tex]v = volume[/tex]

So, we have:

Silicon:

[tex]m = 15.70g[/tex]

[tex]v = 10.1mL[/tex] --- calculated in (a)

Density (d):

[tex]d = \frac{15.70g}{10.1mL}[/tex]

[tex]d = 1.55g/mL[/tex]

Tin:

[tex]m = 50.07g[/tex]

[tex]v = 9.0mL[/tex] --- calculated in (a)

Density (d):

[tex]d = \frac{50.07g}{9.0mL}[/tex]

[tex]d = 5.56g/mL[/tex]

Lead:

[tex]m = 71.47g[/tex]

[tex]v = 7.5mL[/tex] --- calculated in (a)

Density (d):

[tex]d = \frac{71.47g}{7.5mL}[/tex]

[tex]d = 9.53g/mL[/tex]

Answer:

a.cocentration es la respuesta

Answer:

2nd option

Explanation:

Answer:

C - Wind

Explanation:

its C or wind because global wind systems control the surface water

Answer:

Wind

Explanation:

surface water from oceans move from the wind I assume it is the same for all bodies of water

Answer:

heat transfer

Answer:

23

Explanation:

there are 23 pairs of chromosomes

46 individula chromosomes

but each parnet contribute one chromosome to each pair

Answer:

23 :)

Explanation:

The molar concentration of the original HF  solution : 0.342 M

Given

31.2 ml of 0.200 M NaOH

18.2 ml of HF

Required

The molar concentration of HF

Solution

Titration formula

M₁V₁n₁=M₂V₂n₂

n=acid/base valence (amount of H⁺/OH⁻, for NaOH and HF n =1)

Input the value :

[tex]\tt 0.2\times 31.2\times 1=M_2\times 18.25\times 1\\\\M_2=0.342[/tex]

Answer:

A. carrots look better when given more water

Answer:

V₂ = 46.34 mL

Explanation:

Given data:

Initial temperature = 273 K

Initial volume = 50.0 mL

Final temperature = 253 K

Final volume = ?

Solution:

The given problem will be solve through the Charles Law.

Charles Law

"The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure"

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

by putting values in formula,

V₁/T₁ = V₂/T₂

V₂ = V₁T₂/T₁  

V₂ = 50.0 mL × 253 K / 273 k

V₂ = 12650 mL.K / 273 K

V₂ = 46.34mL

Answer:

1) Mass = 18.864 g

2) V =  2.47 L

Explanation:

1) Given data:

Mass of water produced = ?

Mass of SnO₂ react = 79.0 g

Solution:

SnO₂ + 2H₂   →      Sn + 2H₂O

Number of moles of SnO₂:

Number of moles = mass/molar mass

Number of moles = 79.0 g/ 150.71 g/mol

Number of moles = 0.524mol

Now we will compare the moles of SnO₂ and H₂O

                 SnO₂         :        H₂O

                    1             :          2

                  0.524      :         2/1×0.524 =1.048 mol

Mass of water:

Mass = number of moles × molar mass

Mass = 1.048 mol × 18 g/mol

Mass = 18.864 g

2) Given data:

Volume of oxygen required = ?

Volume of C₃H₈ combust at STP = 0.499 L

Solution:

Chemical equation:

C₃H₈ + 5O₂     →      3CO₂ + 4H₂O

Number of moles of C₃H₈:

PV = nRT

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

1 atm × 0.499 L = n × 0.0821 atm.L /mol.K × 273.15 K

0.499 L atm.L = n × 22.43 atm.L /mol

n = 0.499 L atm.L / 22.43 atm.L /mol

n = 0.022 mol

Now we will compare the moles of propane and oxygen.

                  C₃H₈        :           O₂

                       1          :           5

                    0.022    :          5/1×0.022 = 0.11 mol

Volume of oxygen required:

PV = nRT

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

1 atm ×  V = 0.11 mol × 0.0821 atm.L /mol.K × 273.15 K

1 atm ×  V  = 2.47 atm.L

V = 2.47 atm.L  / 1 atm

V =  2.47 L

Answer: I think its A? im not completely sure though!!

Explanation:

Answer:

39.13

Explanation:

To find that atomic mass of this potassium, we follow the steps below:

 Given parameters:

Abundance of K - 39  = 93.26%

Mass of K - 39  = 39

Abundance of K - 41  = 6.73%

Mass of K - 41 = 41

To find the average atomic mass;

Average atomic mass  =( mass x abundance of k -39 ) +( mass abundance of k- 41)

Average atomic mass =  (39 x  93.26%) + (41 x6.73%  )  = 39.13

STP = standard temperature and pressure

Use the formula:

d = MP/RT

where:

d = density = 1.25 g/L

M = molar mass (unknown)

P = pressure = 1 atm (standard pressure)

R = universal gas constant = 0.8206 L*atm/mol*K

T = temperature = 0C or 293.15 K (standard temperature)

1.25 g/L = M*(1 atm)/(0.08206 L*atm/mol*K)*(273.15 K)

M = 28.0 grams/mol

Answer:

A.

Explanation:

sana makatulong follow mo ako please

Explanation:

The group number in the periodic table represents number of valence electrons of the elements in a certain group.

Group 1 : 2,8,1

Group 2 : 2,8,8,2

Group 3 : 2,8,3

Group 4: 2,4

Group 7 : 2,8,7

Answer:

 2, 8 7                7 valence electrons        Group 7

 2, 8 , 1              1 valence electrons         Group 1

 2 8 3               3 valence electrons         Group 3

  2  4               4 valence electrons         Group 4

 2 8 8 2            2 valence electrons         Group 2

Explanation:

The valency of an electronic configuration of an atom can be used to determine the group an element belongs.

The valency is the number of outermost shell electrons an atom contains.

 So;

 2, 8 7                7 valence electrons        Group 7

 2, 8 , 1              1 valence electrons         Group 1

 2 8 3               3 valence electrons         Group 3

  2  4               4 valence electrons         Group 4

 2 8 8 2            2 valence electrons         Group 2

Answer:

6. O₂ + Cu —> CuO

7. H₂ + Fe₂O₃ —> H₂O + Fe

8. O₂ + H₂ — > H₂O

9. H₂S + NaOH —> Na₂S + H₂O

10. Al + HCl —> H₂ + AlCl₃

Explanation:

6. Oxygen gas react with solid copper metal to form copper(II) oxide

Oxygen gas => O₂

Copper => Cu

copper(II) oxide => CuO

The equation is:

O₂ + Cu —> CuO

7. hydrogen gas and iron(III) oxide powder react to form liquid water and solid iron power

hydrogen gas => H₂

Iron(III) oxide => Fe₂O₃

Water => H₂O

Iron => Fe

The equation is:

H₂ + Fe₂O₃ —> H₂O + Fe

8. Oxygen gas react with hydrogen gas to form liquid water

Oxygen gas => O₂

hydrogen gas => H₂

Water => H₂O

The equation is:

O₂ + H₂ — > H₂O

9. Hydrogen sulphide gas is bubbled through a sodium hydroxide solution to produce sodium sulphide and liquid water

hydrogen sulphide => H₂S

sodium hydroxide => NaOH

Sodium sulphide => Na₂S

Water => H₂O

The equation is:

H₂S + NaOH —> Na₂S + H₂O

10. Hydrogen gas and aluminum chloride solutions are produced when solid aluminum react with hydrochloric acid

Aluminum => Al

Hydrochloric acid => HCl

hydrogen gas => H₂

Aluminum chloride => AlCl₃

The equation is:

Al + HCl —> H₂ + AlCl₃