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2 years ago

Calculate the number of molecules in 0.75 moles of CH₄. x 10²³ molecules

Chemistry

1 answer:

spin [16.1K]2 years ago

7 0

Ans :4.5 * 10²³ molecules

Given:

Moles of CH4 = 0.75

To determine;

The number of molecules of CH4 in 0.75 moles

Explanation:

1 mole of CH4 contains Avogadro's number i.e. 6.023*10²³ molecules

Therefore, 0.75 moles would correspond to :

= 0.75 moles * 6.023*10²³ molecules/1 mole

= 4.5 * 10²³ molecules

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A cube has a mass of 42 grams and a volume of 15 cubic centimeters. What is it’s density?

deff fn [24]

Answer:

2.8g/cm³

Explanation:

Given parameters:

Mass of cube = 42g

Volume of cube = 15cm³

Unknown:

Density of the cube = ?

Solution:

Density is defined as the mass per unit volume of a substance. It is mathematically expressed as:

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

So;

Density = $\frac{42}{15}$ = 2.8g/cm³

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2 years ago

Which lists the elements in order from least conductive to most conductive?

Savatey [412]

Answer: Option (A) is the correct answer.

Explanation:

Nitrogen is a non-metal and it is known that non-metals do not conduct electricity. Thus, it will be least conductive out of the given options.

Whereas antimony (Sb) is a metalloid. Metalloid are the substance that show properties of both metals and non-metals. Thus, antimony will conduct electricity.

On the other hand, bismuth (Bi) is a metal hence, it will conduct electricity.

Thus, we can conclude that the order from least conductive to most conductive will be nitrogen (N), antimony (Sb), bismuth (Bi).

7 0

2 years ago

Read 2 more answers

Read that From picture and tell me the answer please

Dafna11 [192]

Answer:

1g Hydrogen

Explanation:

<h3>Getting to the equation:</h3>

Calcium in water reacts vigorously to give a cloudy white Precipitate (compound) called Calcium hydroxide alongwith the evolution of Hydrogen gas.

$\boxed{ \mathsf{Ca + H_2O \rightarrow Ca(OH)_2 + H_2}}$

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Balancing the equation: </h3>

This reaction is not in it's balanced form! The number of atoms of Hydrogen on the left is 2 while that on the right is 4,I.e.,they're not equal.

Adding a 2 in front of H2O solves the problem by making the number of atoms of each element on both the sides equal.

$\mathsf{Ca +2 H_2O \rightarrow Ca(OH)_2 + H_2}$

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Observations:</h3>

Looking into the equation more carefully, we see:

1 atom of Calcium reacts with 2 molecules of water to give 1 molecule of Calcium Hydroxide alongwith 1 molecule of Hydrogen gas.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Gram atomic and molecular masses </h3>

Mass of one atom of Calcium = it's gram atomic mass

= 40 g

Mass of one "molecule" of Hydrogen

= it's Gram molecular mass

= gram mass of one atom × number of atoms in one molecule

= 1 × 2

= 2 g

So,

according to our observation:

One atoms of Calcium gives one molecule of Hydrogen (during the particular reaction)

=> 40g of Calcium gives = 2g of Hydrogen

•°• 1 g of Calcium gives = $\frac{2}{40}$

= $\frac{1}{20}$ g Hydrogen

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Answer:</h3>

We're provided with 20g of Calcium,

=> 20g of Calcium gives = 20 × $\frac{1}{20}$ g H2

= 1 g H2

_______________

Hope this helps!

6 0

2 years ago

Wht is this called N which chain does it belong

german

Answer:

national

Explanation:

I don't understand, I'm sorry

5 0

3 years ago

If a stable element has an atomic number of 8, how many electrons does it have? HELP PLEASE!!!!!

mash [69]

8 because atomic number is the same as number of protons, protons and electrons have the same amount so that the element is neither positive nor negative.

6 0

2 years ago