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3 years ago

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Dmitri Mendeleev and Henry Moseley developed their periodic tables about forty years apart. During that time, many discoveries i

n chemistry were made. Which fact was most likely discovered between the time of Mendeleev’s table and the time of Moseley’s table that helped Moseley develop his version? Atomic mass is the average mass of different samples of the same element. Different elements can have similar chemical properties even if their atomic masses are different. The number of protons in an atom is different than the atom’s total mass. Protons strongly affect an element’s atomic mass, while the electrons in atoms do not.

2 answers:

Travka [436]3 years ago

6 0

Answer:

Its C

Explanation:

Sindrei [870]3 years ago

4 0

Answer:

The first one I think

Explanation:

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Assume a gasoline is isooctane, which has a density of 0.692 g/ml. What is the mass of 3.8 gal of the gasoline (1 gal = 3.78 l)?

sveticcg [70]

Density is the ratio of mass to the volume.

The mathematical expression is given as:

$density=\frac{mass}{volume}$

Now, density of isooctane = $0.692 g/mL$

Volume = $3.8 gal$

Since, 1 gallon = 3.78 L

So, 3.8 gal = $3.78 L\times 3.8$

= $14.364 L$

As, 1 L = 1000 mL

Therefore, $14.364 L$ = $14.364 L\times 1000 mL$

Volume in mL = $14364 mL$

Put the values,

$0.692 g/mL=\frac{mass}{14364 mL}$

$m = 0.692 g/mL\times 14364 mL$

= $9939.888 g$

Hence, mass of 3.8 gal of the gasoline is $9939.888 g$ .

6 0

3 years ago

How many grams of CO2 are in 6 mol of the compound (this is a science question)?

denpristay [2]

0.136 C02 would be your answer

5 0

3 years ago

Read 2 more answers

A sample of 1.000 g of a compound containing carbon and hydrogen reacts with oxygen at elevated temperature to yield 0.692 g H₂O

ollegr [7]

Answer :

(a) 1.000 g of compound containing carbon and hydrogen is, 0.922 g and 0.0769 g respectively.

(b) There is no other element present in the compound.

Explanation :

(a) Now we have to determine the masses of C and H in the sample.

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

$C_xH_y+O_2\rightarrow CO_2+H_2O$

where, 'x' and 'y' are the subscripts of Carbon and hydrogen respectively.

We are given:

Mass of $CO_2=3.381g$

Mass of $H_2O=0.692g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 3.381 g of carbon dioxide, $\frac{12}{44}\times 3.381=0.922g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 0.692 g of water, $\frac{2}{18}\times 0.692=0.0769g$ of hydrogen will be contained.

Thus, 1.000 g of compound containing carbon and hydrogen is, 0.922 g and 0.0769 g respectively.

(b) Now we have to determine the compound contain any other elements or not.

Mass carbon + Mass of hydrogen = 0.922 g + 0.0769 g = 0.999 g ≈ 1 g

This means that there is no other element present in the compound.

3 0

3 years ago

What is the mass of KOH found in a 785 mL of a 1.43 M solution of KOH

My name is Ann [436]

Molarity is defined as the ratio of number of moles to the volume of solution in litres.

The mathematical expression is given as:

$Molarity = \frac{Number of moles}{volume of solution in litres}$

Here, molarity is equal to 1.43 M and volume is equal to 785 mL.

Convert mL into L

As, 1 mL = 0.001 L

Thus, volume = $785\times 0.001$ = 0.785 L

Rearrange the formula of molarity in terms of number of moles:

$Number of moles =molarity\times volume of solution in litres$

n = $1.43 M \times 0.785 L$

= 1.12255 mole

Now, Number of moles = $\frac{mass in g}{molar mass}$

Molar mass of potassium hydroxide = 56.10 g/mol

1.12255 mole = $\frac{mass in g}{56.10 g/mol}$

mass in g = $1.12255 mole\times 56.10 g/mol$

= 62.97 g

Hence, mass of $KOH$ = 62.97 g

7 0

3 years ago

Select the correct answer. Two charged objects, A and B, exert an electric force on each other. What happens if the distance bet

VikaD [51]

Answer:

The electric force between them decreases

Explanation:

The force between two charged particle is given by :

$F=\dfrac{kq_1q_2}{r^2}$

Where

r is the distance between charges

If the distance between the charges is increased, the electric force gets decreased as there is an inverse relation between force and distance.

Hence, the correct option is (c) "The electric force between them decreases"

7 0

2 years ago