Chemistry, 09.12.2020 18:10 nanaflower321

Help me please:((( Ashley disagrees with her teacher that Earth’s surface has changed over the centuries. She says that it is difficult to believe because no one was around during this time to see it with their own eyes, but she can see the 7 continents that make up earth’s surface now. Her classmates try to explain the evidence that can be used to support this theory of continental drifting. Which of the following best supports the theory of continental drift?

Question 5 options:

Classmate #1 says that the landmass called Pangea existed and we know this because all of the continents such as North America and South America fit together like puzzle pieces.

Classmate #2 says that the landmass called Pangea existed and we know this because fossil evidence found in Africa were only in Africa.

Classmate #3 says that the landmass called Pangea existed and we know this because fossils of similar animals were discovered on different continents that fit together like puzzle piece.

Classmate #4 says that the landmass called Pangea existed and we know this because fossils of similar animals were discovered on different continents that do not fit together like puzzle piece.

Answers: 3

Show answers

Answers

Answer from: Quest

Ok where is the image ?

Answer from: Quest

the right answer is c i just did the question.

Answer from: Quest

the missing options are :

(1) lower boiling point and a lower freezing point(2) lower boiling point and a higher freezing point(3) higher boiling point and a lower freezing point(4) higher boiling point and a higher freezing point

answer : the correct answer is option (3) higher boiling point and a lower freezing point

explanation :

when a non volatile solute is added to a solvent like water, it results in elevation of boiling point.

let us find the increase in boiling point of water when cacl₂ is added to water to make a solution of 1 m

step 1 : find molality of the solution

let us assume we have 1 l of solution.

$m = \frac{moles (solute)}{l ( solution)}$

$1 m = \frac{moles (cacl_{2})}{1 l }= 1 mol cacl_{2}$

let us convert this to grams of cacl₂.

molar mass of cacl2 is 111 g/mol

grams of cacl₂ = $1 mol \times \frac{111g}{mol} = 111 g cacl_{2}$

mass of solute = 111 g

assuming density of solution same as water which is 1g/ml we have ,

mass of solution = density * volume

mass of solution = $\frac{1g}{ml} \times 1000 ml = 1000 g$

mass of solution = mass of solvent + mass of solute

mass of solute = 1000g - 111g

mass of solute 889 g = 0.889 kg

the molality of the solution can be calculated as

$molality = \frac{mol (solute)}{kg ( solvent)}$

$molality = \frac{1mol}{0.889kg}$

molality = 1.12 m

step 2 : find boiling point elevation.

the elevation in boiling point is calculated as

$\bigtriangleup t_{b} = i \times k_{b} \times m$

here δtb = boiling point elevation

i = vant hoff factor which is the number of ions formed by the solute .

cacl₂ dissociates as $cacl_{2} \rightarrow ca^{2+} + 2 cl^{-}$

it forms 3 ions . therefore,

i = 3

m = molality which is 1.12 m

kb is constant for a given solvent. for water it is 0.512

$\bigtriangleup t_{b} = 3 \times 0.512 \times 1.12$

$\bigtriangleup t_{b} = 1.7$

the boiling point of water increases by 1.7 °c

step 3: find freezing point depression.

when a non volatile solute is added to water, it results in decrease in freezing point.

the formula to find freezing point depression is

$\bigtriangleup t_{f} = i \times k_{f} \times m$

kf is constant for water and its value is 1.86

$\bigtriangleup t_{f} = 3 \times 1.86 \times 1.12$

$\bigtriangleup t_{f} = 6.2$

the freezing point of water decreases by 6.2 °c

therefore we can say that, the solution will have a higher boiling point and a lower freezing point

Answer from: Quest

Ithink the correct answer is 3

Another question on Chemistry

Chemistry, 22.06.2019 09:50

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange

Answers: 1

Answer

Chemistry, 22.06.2019 10:10

Stage in which a typical star has completely stopped fusion

Answers: 1

Answer

Chemistry, 22.06.2019 15:30

The reactions of photosynthesis occur in the of plant cell? a.mitochondria. b. lysosomes. c. chloroplasts. d. chlorophyll

Answers: 1

Answer

Chemistry, 22.06.2019 20:10

The lattice enthalpy (formation of ionic solid from ions in the gas phase) for agcl(s) is -916 kj/mol and the hydration enthalpy (dissolution of gaseous ions into water) is -850 kj/mol. how much heat (in joules) is involved in forming 1l of saturated agcl solution (1.8 × 10-4 g / 100 ml water) by dissolving agcl(s)? assume solution volume does not change much upon dissolution. the equations are given below. ag+(g) + cl−(g) æ agcl(s)

Answers: 3

Answer

You know the right answer?

Help me please:((( Ashley disagrees with her teacher that Earth’s surface has changed over the cent...

Questions