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4 years ago

The mass number of an element is equal to ____.

Chemistry

2 answers:

melisa1 [442]4 years ago

4 0

Mass number is the total number of protons and neutrons in the nucleus

nlexa [21]4 years ago

3 0

Answer: b. the total number of protons and neutrons in the nucleus

Explanation:

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

In an atom, when neutrons or protons are lost or gains, it directly affects the mass number of an atom.

Atomic number is defined as the number of protons or number of electrons that are present in an atom.

Atomic number = Number of electrons = Number of protons

Thus the mass number of an element is equal to the total number of protons and neutrons in the nucleus.

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Microwave radiation has a wavelength on the order of 1.0 cm. Calculate the frequency and the energy of a single photon of this r

denis23 [38]

Answer :

(1) The frequency of photon is, $3\times 10^{10}Hz$

(2) The energy of a single photon of this radiation is $1.988\times 10^{-23}J/photon$

(3) The energy of an Avogadro's number of photons of this radiation is, 11.97 J/mol

Explanation : Given,

Wavelength of photon = $1.0cm=0.01m$ (1 m = 100 cm)

(1) Now we have to calculate the frequency of photon.

Formula used :

$\nu=\frac{c}{\lambda}$

where,

$\nu$ = frequency of photon

$\lambda$ = wavelength of photon

c = speed of light = $3\times 10^8m/s$

Now put all the given values in the above formula, we get:

$\nu=\frac{3\times 10^8m/s}{0.01m}$

$\nu=3\times 10^{10}s^{-1}=3\times 10^{10}Hz$ $(1Hz=1s^{-1})$

The frequency of photon is, $3\times 10^{10}Hz$

(2) Now we have to calculate the energy of photon.

Formula used :

$E=h\times \nu$

where,

$\nu$ = frequency of photon

h = Planck's constant = $6.626\times 10^{-34}Js$

Now put all the given values in the above formula, we get:

$E=(6.626\times 10^{-34}Js)\times (3\times 10^{10}s^{-1})$

$E=1.988\times 10^{-23}J/photon$

The energy of a single photon of this radiation is $1.988\times 10^{-23}J/photon$

(3) Now we have to calculate the energy in J/mol.

$E=1.988\times 10^{-23}J/photon$

$E=(1.988\times 10^{-23}J/photon)\times (6.022\times 10^{23}photon/mol)$

$E=11.97J/mol$

The energy of an Avogadro's number of photons of this radiation is, 11.97 J/mol

3 0

3 years ago

Read 2 more answers

The specific heat of copper is 0.093 cal/g0C. Calculate the temperature change that occurs if 28 g of copper at 25 0C absorbs 58

Umnica [9.8K]

Answer:

22.27 °C = ΔT

Explanation:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m × c × ΔT

Given data:

mass = 28 g

heat absorbed = 58 cal

specific heat of copper = 0.093 cal/g .°C

temperature change =ΔT= ?

Solution:

Q = m × c × ΔT

58 cal = 28 g × 0.093 cal /g.°C × ΔT

58 cal = 2.604 cal.°C × ΔT

58 cal / 2.604 cal .°C = ΔT

22.27 °C = ΔT

5 0

3 years ago

When a 120 g sample of aluminum absorbs 9612 of heat energy, its temperature increases from 25°C to 115°C. Find the specific hea

lesantik [10]

<h3>Answer:</h3>

0.89 J/g°C

<h3>Explanation:</h3>

Concept tested: Quantity of heat

We are given;

Mass of the aluminium sample is 120 g
Quantity of heat absorbed by aluminium sample is 9612 g
Change in temperature, ΔT = 115°C - 25°C

= 90°C

We are required to calculate the specific heat capacity;

We need to know that the quantity of heat absorbed is calculated by the product of mass, specific heat capacity and change in temperature.

That is;

Q = m × c × ΔT

Therefore, rearranging the formula we can calculate the specific heat capacity of Aluminium.

Specific heat capacity, c = Q ÷ mΔT

= 9612 J ÷ (120 g × 90°C)

= 0.89 J/g°C

Therefore, the specific heat capacity of Aluminium is 0.89 J/g°C

4 0

3 years ago

What is the empirical formula of C3H6N2

Evgen [1.6K]

Answer:

The empirical formula of the compound C₃H₆N₂ is C₃H₆N₂

Explanation:

The empirical formula of a compound is the formula of the compound given in the (smallest) whole number ratio of the elements of the compound

The empirical formula of S₂O₂ is SO

The empirical formula of C₃H₆O₃ is CH₂O

The given compound's molecular formula is C₃H₆N₂

The smallest whole number ratio of of the elements of the compound is 3:6:2, therefore, the empirical formula of the compound C₃H₆N₂ is C₃H₆N₂.

4 0

3 years ago

Which is a renewable resource?A.gold B.copper C.timber D.natural gas

romanna [79]

Answer: D. Natural Gas

Explanation:

7 0

3 years ago