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Zanzabum
3 years ago
12

A certain atom has an atomic number of four. how many protons does it have? 8 2 0 4 description

Chemistry
2 answers:
Contact [7]3 years ago
4 0
4 protons the number of proton has the same number of electron [which is the same as atomic number]
const2013 [10]3 years ago
3 0
4 protons the number of proton has the same number of electron
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Select the correct answer from the drop-down menu. a scientist digs up sample of arctic ice that is 458,000 years old. he takes
Jlenok [28]

The original mass of krypton 81 that is present in the ice is 6.70 grams.

<h3>How do we calculate original mass?</h3>

Original mass of any substance will be calculated as below for the decomposition reaction is:

N = N₀(1/2)ⁿ, where

N = remaining mass of krypton-81 = 1.675g

N₀ = original mass of krypton-81 = ?

n will be calculated as:
n = T/t, where

T = total time period = 458,000 years

t = half life time = 229,000 years

n = 458,000/229,000 = 2

Now putting all these values on the above equation, we get

N₀ = 1.675 / (1/2)²

N₀ = 6.70 g

Hence required mass is 6.70 g.

To know more about half life time, visit the below link:
brainly.com/question/2320811

8 0
3 years ago
PLS HELP!
Nadya [2.5K]

Question 1

Fe(III) forms a chelate complex with salicylic acid which has purple color. therefore, when a solution is made either with salicylic acid or with aspirin having trae amount of salicylic acid in it, we see color formation in solution due to the resulting complex formed.

Question 2

The Fe(III) itself absorbs some light and gives an absorbance value for the solution. Therefore, it is necessary to blank the spectrophotometer with a Fe(III) solution prior to measurement of test solutions.

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The word science is derived from latin word..........which means............​
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Scientia, meaning knowledge and skill
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Read 2 more answers
Se mezclan 20 gramos de agua (1cal/g°C) a 40 °C con 15 gramos de alcohol (0,58cal/g°C) a 30 °C. ¿Cuál ha sido la temperatura de
madreJ [45]

Answer:

T_{EQ}=37\°C

Explanation:

¡Hola!

En este caso, para los problemas de equilibrio térmico, consideramos que la energía liberada por la sustancia que inicialmente está caliente (agua), es absorbida por la sustancia que inicialmente está fría (alcohol); thus, we can write:

Q_{agua}=-Q_{alcohol}

La cual puede ser escrita en términos de masa, calor specifico y temperaturas:

m_{agua}C_{agua}(T_{EQ}-T_{agua})=-m_{alcohol}C_{alcohol}(T_{EQ}-T_{alcohol})

De este modo, al resolver para la temperature de equilibrio térmico, obtenemos la siguiente expresión:

T_{EQ}=\frac{m_{agua}C_{agua}T_{agua}+m_{alcohol}C_{alcohol}T_{alcohol}}{m_{agua}C_{agua}+m_{alcohol}C_{alcohol}}

Así, al reemplazar los valores en esta, obtenemos:

T_{EQ}=\frac{(20g)(1cal/g\°C)(40\°C)+(15g)(0.58cal/g\°C)(30\°C)}{(20g)*(1cal/g\°C)+(15g)(0.58cal/g\°C)} \\\\T_{EQ}=37\°C

¡Saludos!

3 0
3 years ago
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