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3 years ago

explain how chemists can state with certainty that no one will discover an element between sulfur and chlorine?

1 answer:

4 0

<span>Elements are distinguished based on their number of protons. Chlorine has exactly one proton more than sulfur. Since there cannot be fractions of protons, there can be no element between sulfur and chlorine on the periodic table.</span>

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What is atomic mass of an element stands for

Dovator [93]

Mass is a basic property of matter and is made of atoms. Atoms are made of electrons, protons, and neutrons. Protons and neutrons make up the majority of the mass in an atom. Atoms may vary in the number of neutrons they have (called isotopes), and therefore the exact atomic mass may vary from atom to atom

3 0

3 years ago

Which of the following is not a physical change?

Dimas [21]

When you burn paper you are chemically altering it so that is the correct answer. When you do all the other choices all of the components stay the same. Just because it changes shapes doesn't mean it'll change chemically toom

6 0

3 years ago

What is the volume of 0.20 moles of helium at STP?

stealth61 [152]

The volume of 0.20 moles of helium at STP is 4.5 liters.

Explanation:

Given:

Number of moles = 0.20 moles

To Find:

The volume of Helium at STP =?

Solution:

According to ideal gas law

PV = nRT

where

P is pressure,

V is volume,

n is the number of moles

R is the gas constant, and

T is temperature in Kelvin.

The question already gives us the values for p and T ,because helium is at STP. This means that temperature is 273.15 K and pressure is 1 atm .

We also already know the gas constant. In our case, we'll use the value of

0.08206 L atm/K mol since these units fit the units of our given values the best

On substituting these values we get

$1 atm \times V = 0.20 moles \times 0.08206 L atm/K mol$

$V = \frac{0.20 moles \times 0.08206 L atm/K mol }{ 1 atm}$

$V = \frac{4.482}{1}$

V = 4.5 Liters

7 0

3 years ago

How many moles are 4.20 * 10 ^ 25 atoms of Ca?

aleksandr82 [10.1K]

Answer:

~69.744 moles of Ca

Explanation:

Using Avogadro's constant , we know that:

1 mole = 6.022 x 10^23 atoms

S0, the number of moles in 4.20 x 10^25 atoms of Ca:

=(4.20 x 10^25 x 1 )/(6.022 x 10^23)

~69.744 moles of Ca

Q2:How many atoms are in 0.35 moles of oxygen?

1 mole = 6.022 x 10^23 atoms

S0, the number of atoms in 0.35 moles of oxygen:

=[0.35 x (6.022 x 10^23)]

=2.1077 x 10^23 atoms of Oxygen

Hope it helps:)

4 0

2 years ago

Perform the following operation and express the answer in scientific notation. 7.0x10^3x1.1x10^7

dimulka [17.4K]

Answer:

The answer is: $7.7\times10^{10}$

Explanation:

Scientific notation is of the kind: $a.bc\times10^{x}$

The given calculation:

$7.0\times10^{3}\times1.1\times10^{7}=(7\times1.1)\times10^{(3+7)}$

$=7.7\times10^{10}$

Therefore, the answer in scientific notation is: $7.7\times10^{10}$

4 0

3 years ago