All categories

2 years ago

A sample has an atomic number is 18 and atomic mass 33, what is the number of neutrons?

Chemistry

1 answer:

Ivenika [448]2 years ago

3 0

Answer:

15 neutrons

Explanation:

the atomic mass shows the amount of neutrons and protons added together

the atomic number shows us how many protons they are (you can also find out how many electrons a element has by looking at its atomic number as it will have the same amount of protons)

so to find the amount of neutrons the sample has you have you subtract the atomic number which is the amount of protons from the mass number which tells us the amount of neutrons and protons added together but we only need the neutrons that's why we subtract it

33-18=15

You might be interested in

How many grams of kbr must be dissolved to make 25.0 ml of a solution that has a molarity of 0.85 m?

lyudmila [28]

Molarity is defined as the number of moles of solute in 1 L of solution
molarity of solution to be prepared is 0.85 M
this means that there should be 0.85 mol of KBr in 1 L of solution
if 1 L contains - 0.85 mol
then 25.0 mL should contain - 0.85 mol / 1000 mL x 25.0 mL = 0.0213 mol
mass of KBr - 0.0213 mol x 119 g/mol = 2.53 g
mass of KBr that should be dissolved in 25.0 mL is 2.53 g

4 0

3 years ago

Determine the number of atoms in 41.0 grams of calcium, Ca. (The mass of one mole of calcium is 40.08 g.)

Dovator [93]

Hi there!

Let me know if you have questions about my answer:

6.15 × 10²⁴

Explanation:

To find the number of atoms, divide the mass of calcium (m) by its molar mass (MM). This will give you the number of moles of calcium (n).

$n = m/MM$ Start with a formula

$=\frac{41.0g}{40.08g/mol}$ Substitute values from the question

$= \frac{41.0g*1mol}{40.08g}$ Simplify

$= \frac{41.0mol}{40.08}$ Cancel out the units "g"

$= 1.022...mol$ Number of moles of calcium, with 4 significant figures

Then, multiply the number of moles of calcium (n) by Avogadro's number ( $N_{A}$ ) to find the number of calcium atoms.

$Number.of.Ca=n*N_{A}$ Start with a formula

$= 1.022mol*\frac{6.022*10^{23}Ca}{1mol}$ Substitute values from the question

$= \frac{1.022mol*6.022*10^{23}Ca}{1mol}$ Simplify

$= 1.022*(6.022*10^{23}Ca)$ Cancel out the units "mol"

$= 6.154*10^{24} Ca$ Multiply, leave one extra digit to help round. "4" tells you to round down.

$= 6.15*10^{24} Ca$ Final answer to 3 significant figures*

*When multiplying and dividing numbers, your final answer will have the same number of significant figures as the number with the least number of significant figures in the question.

40.08 has 4 significant figures. 41.0 has 3 significant figures. So, you want 3 significant figures in your final answer.

I hope this helps!

Learn more about Avogadro's number here:

brainly.com/question/1445383

Check out another answer that uses significant figures:

brainly.com/question/3721164

7 0

3 years ago

Nickel is extracted from nickel oxide by reduction with carbon.

meriva

Answer:

Nickel is extracted from nickel oxide by reduction with carbon. Nickel is a metal which react with atmospheric oxygen which is very reactive in order to protect the inner surface of metal. Carbon extract oxygen which is attached to the nickel in the form of nickel oxide because carbon is more reactive so it made a chemical bonds with oxygen and nickel oxide is converted into a pure nickel.

3 0

3 years ago

A student prepares a model of multicellular organisms which statement best explains the difference between tissues and organs an

olga_2 [115]

Answer:

C.)organs are a group of two or more different types of tissues that work together to perform a specific function

Explanation:

Cells of similar function are grouped together into tissues. For example, cardiac muscle tissue is present only in the heart, and made up of specialised cells called cardiomyocytes, or cardiac muscle cells. These cells contract to pump blood around the body.

The heart is an organ, consisting of multiple types of tissue including cardiac muscle tissue, connective tissue, blood vessels and epithelial tissue. Therefore, organs represent a group of at least two types of tissue that work together to carry out functions in the body.

7 0

3 years ago

Which mixtures could be separated using filtration? Check all that apply.

cestrela7 [59]

Answer:

smoky air

fresh river water

Explanation:

just did the assignment

5 0

3 years ago

Read 2 more answers