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Ira Lisetskai [31]
3 years ago
12

The mass number of an atom is 15, and its atomic number is 7. The atom probably has... 8 neutrons in the nucleus. about as much

mass in electrons as in protons. at least 15 electrons. 7 units of negative charge in the nucleus. 7 electrons in the nucleus.
Chemistry
1 answer:
Artist 52 [7]3 years ago
3 0

Answer: Option (a) is the correct answer.

Explanation:

Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

For example, given atom has mass number as 15 and its atomic number is 7.

Therefore, number of neutrons present in it will be calculated as follows.

                    Mass number = no. of protons + no. of neutrons

                         15 = 7 + no. of neutrons

                    no. of neutrons = 15 - 7

                                               = 8

Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.

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Using the thermodynamic information in the ALEKS Data tab, calculate the standard reaction free energy of the following chemical
julia-pushkina [17]

Answer:

43.0 kJ

Explanation:

The free energy (ΔG) measures the total energy that is presented in a thermodynamic system that is available to produce useful work, especially at thermal machines. In a reaction, the value of the variation of it indicates if the process is spontaneous or nonspontaneous because the free energy intends to decrease, so, if ΔG < 0, the reaction is spontaneous.

The standard value is measured at 25°C, 298 K, and the value of free energy varies with the temperature. It can be calculated by the standard-free energy of formation (G°f), and will be:

ΔG = ∑n*G°f products - ∑n*G°f reactants, where n is the coefficient of the substance in the balanced reaction.

By the balanced reaction given:

2NOCl(g) --> 2NO(g) + Cl2(g)

At ALEKS Data tab:

G°f, NOCl(g) = 66.1 kJ/mol

G°f, NO(g) = 87.6 kJ/mol

G°f, Cl2(g) = 0 kJ/mol

ΔG = 2*87.6 - 2*66.1

ΔG = 43.0 kJ

6 0
3 years ago
The number at the end of an isotope’s name is the ____ number. A) Atomic B)neutron C)mass D)electron
storchak [24]
 each isotope of a given element has a different mass number. For example, carbon-12, carbon-13<span> and carbon-</span>14<span> are </span>three<span> isotopes of the element carbon with mass numbers </span>12<span>, </span>13<span> and </span>14<span> </span>
3 0
3 years ago
Read 2 more answers
How does matter change phase?
crimeas [40]

Answer:

Phase changes typically occur when the temperature or pressure of a system is altered. When temperature or pressure increases, molecules interact more with each other. When pressure increases or temperature decreases, it's easier for atoms and molecules to settle into a more rigid structure.

Explanation:

Hope it helps UvU

7 0
2 years ago
In the following equation:
Luda [366]

Answer:

FeCl₃

Explanation:

                 4FeCl₃  +   3O₂     => 2Fe₂O₃+ 6Cl₂

Given =>  7moles     9moles

A simple way to determine which reagent is the limiting reactant is to convert all given data to moles then divide by the respective coefficients of the balanced equation. The smaller value will be the limiting reactant.

                 4FeCl₃     +   3O₂     => 2Fe₂O₃+ 6Cl₂

Given =>  7/4 = 1.75*     9/3 = 3

*Smaller value => FeCl₃ is limiting reactant.  

NOTE: However, when working problems, one must use original mole values given.

   

7 0
3 years ago
If equal volumes of 0.1 M HCl and 0.2 M TRIS (base form) are mixed together. The pKa of TRIS is 8.30. Which of the following sta
blondinia [14]

Answer:

option D is correct

D. This solution is a good buffer.

Explanation:

TRIS (HOCH_{2})_{3}CNH_{2}

if TRIS is react with HCL it will form salt

(HOCH_{2})_{3}CNH_{2} + HCL ⇆   (HOCH_{2})_{3}NH_{3}CL

Let the reference volume is 100

Mole of TRIS is =  100 × 0.2 = 20

Mole of HCL is =  100 × 0.1 = 10

In the reaction all of the HCL will Consumed,10 moles of the salt will form

and 10 mole of TRIS will left

hence , Final product will be salt +TRIS(9 base)

H = Pk_{a} + log (base/ acid)

8.3 + log(10/10)

8.3

6 0
3 years ago
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