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shusha [124]
3 years ago
15

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

e number of electrons present in an atom?
Chemistry
1 answer:
Zanzabum3 years ago
3 0

<u>Answer:</u> The atomic number of helium atom is 2 and mass number of helium atom is 4.

<u>Explanation:</u>

Atomic number is defined as the number of protons or electrons that are present in a neutral atom.  It is represented by the symbol 'Z'

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.  It is represented by the symbol 'A'

Mass number = Number of protons + Number of neutrons

The general representation of an isotope is given as _Z^A\textrm{X}

where,

A = mass number of element

Z = atomic number of element

X = symbol of the element

We are given:

An isotope of helium having formula of _2^4\textrm{He}

where,

Atomic number of helium = 2 = Number of protons = Number of electrons

Mass number of helium = Number of protons + Number of neutrons

4 = 2 + Number of neutrons

Number of neutrons = 4 - 2 = 2

Hence, the atomic number of helium atom is 2 and mass number of helium atom is 4.

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3 years ago
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Does anyone know what convection,conduction,radiation??
saw5 [17]

Answer:

Conduction is the transfer of thermal energy through direct contact. Convection is the transfer of thermal energy through the movement of a liquid or gas. Radiation is the transfer of thermal energy through thermal emission.

3 0
3 years ago
PLZ HELP!<br><br> How do you think changing the angle of a ramp will affect work done?
kogti [31]

Answer: The steepness of a ramp affects it by making it easier or harder.

Explanation: It's a bit situational. If you were going up a steep ramp with a heavy load, it will increase the work necessary, whereas if you were going down a ramp, it would decrease the work necessary. If you need this simply put, think about biking up and down a hill. It would be easier going down than up.

6 0
3 years ago
The volume of the earth is approximately 1.08326x10 to the 12th power km to the 3rd power. How many liters is this
mafiozo [28]

Here, we are required to determine the volume of the earth which is 1.08326 × 10¹² km³ in liters.

<em>The volume of the earth is approximately</em>,

, 1.08326 × 10²⁴ liters

By conversion factors;

  • <em>1dm³ = 1liter</em>
  • However; <em>1km = 10000dm = 10⁴ </em><em>dm</em>
  • Therefore, 1km³ = (10⁴)³ dm³.

Consequently, 1km³ = 10¹²dm³ = 10¹²liters.

The conversion factor from 1km³ to liters is therefore, c.f = 10¹²liters/km³

Therefore, the volume of the earth which is approximately, 1.08326 × 10¹² km³ can be expressed in liters as;

<em>1.08326 × 10¹² km³ × 10¹²liters/km³ </em>

The volume of the earth is approximately,

1.08326 × 10²⁴ liters.

Read more:

brainly.com/question/16814684

7 0
2 years ago
The number of ions in 17.1 gm of aluminum sulphate Al2 (SO4)3 =….. [Molar mass of Al2 (SO4)3 = 342 gm]
katen-ka-za [31]

Answer:

1.51 X 10^23 ions

Explanation:

The number of ions in 17.1 gm of aluminum sulphate Al2 (SO4)3 =….. [Molar mass of Al2 (SO4)3 = 342 gm]

in one molecule of Al2(SO4)3 there are 5 ions 2 aluminum and 3 sulfate ions

in 2 molecules there are 2X5= 10 ions

in 10 molecules there are 10X5 = 50 ions

molar mass of Al2(SO4)3 = (2 X 26.98) +( 3 X 32.1) + (3 X 4 X 16.0 ) =342.gms = 17.1/342 =0.0500 moles

1  mole =6.02 X 10^23 molecules ( see Avogadros number)

0.0500 moles = 0.0500 X 6.02 X 10^23 molecules =

0.301 X 10^23 molecules = 3.01 X 10^22 molecules

We determined that each molecule of Al2(SO4)3 has 5 ions

so 3.01 X10^22 molecules have 5 X 3.01 X 10^22 ions =

15.05 X 10^22 ions = 1.51 X 10^23 ions

3 0
3 years ago
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