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olasank [31]
3 years ago
7

Use the helium-4 isotope to define atomic number and mass number. why does knowledge of atomic number enable us to deduce the nu

mber of electrons present in an atom
Chemistry
1 answer:
Nuetrik [128]3 years ago
8 0
Helium - 4 isotope has 2 protons and 2 neutrons.

Its atomic number is 2 (the number of protons). Atomic number is the number of protons in the atom of an element and it identifies the element. All the isotopes of an element have the same atomic number (same number of protons). So, all the isotopes of hellium have 2 protons.

The number 4 that identifies the helium - 4 isotope is the mass number, i.e. the number of protons plus the number of neutron. So, helium-4 isotope has 2 protons and 2 neutrons. While, other isotopes of helium have 2 protons but different number of neutrons.

The atomic number enable us to deduce the number of electrons in an atom because the atoms are neutral, which implies that the positive and negative charge are equal. Given that the magnitude of the charge of electons and protons are equal but the sign is opposed (protons are positve and electrons are negative) the number of electrons in the atom equals the number of protonts. That is why the atomic number is also the number of electrons of the atom.
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Carbordum is silicon carbide SiC a very hard material used as an abrasive on sand paper and in other applications. it is prepare
AleksandrR [38]

Answer:

4.5 kilograms of silicon dioxide is required to produce 3.00 kg of SiC.

Explanation:

The balanced equation for the reaction between silicon dioxide and carbon at high temperature is given as:

SiO_2+3C\rightarrow SiC+2CO

1 mole silicon dioxide reacts with 3 moles of carbon to give 1 moles of silicon carbide and 2 moles of carbon monoxide.

Mass of SiC = 3.00kg = 3000.00 g

1 kg = 1000 g

Molecular mass of SiC = 40 g/mol

Moles of SiC = \frac{3000.00 g}{40 g/mol}= 75 mol

According to reaction, 1 mole of SiC is produced from 1 mole of silicon dioxide.

Then 75 moles of SiC will be produce from:

\frac{1}{1}\times 75 mol=75 mol of silicon dioxide.

mass of 75 moles of silicon dioxde:

75 mol\times 60 g/mol=4500 g=4.5 kg

4.5 kilograms of silicon dioxide is required to produce 3.00 kg of SiC.

3 0
3 years ago
Who likes pomegranates
Sergio [31]

Answer:

I LIKE POMEGRANATES

Explanation

A LOT

8 0
3 years ago
Why can filtration not be used to seperate a mixture of 2 liquids ​
Salsk061 [2.6K]

Answer:

Filtration works best when the solute isn't dissolve in the solvent. For instance, sand and water can be seperated through filtration because both compounds do not dissolve with each other. However, sugar and water would not be seperated through filtration as they dissolve with each other.

-google :)

3 0
3 years ago
An isotope of cesium has 55 protons and 78 neutrons. What is the mass number of this isotope?
mixer [17]

The only stable caesium isotope is 133Cs, with 78 neutrons.

Hope this answers your Q

4 0
3 years ago
Calculate the molarity of the solution formed when 0.72 moles of CaBr2 is dissolved in 1.50 L water.
xxTIMURxx [149]

Answer:

The molarity of the formed CaBr2 solution is 0.48 M

Explanation:

Step 1: Data given

Number of moles CaBr2 = 0.72 moles

Volume of water = 1.50 L

Step 2: Calculate the molarity of the solution

Molarity of CaBr2 solution = moles CaBr2 / volume water

Molarity of CaBr2 solution = 0.72 moles / 1.50 L

Molarity of CaBr2 solution = 0.48 mol / = 0.48 M

The molarity of the formed CaBr2 solution is 0.48 M

4 0
3 years ago
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