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3 years ago

What is Artificial selection???

Chemistry

1 answer:

kati45 [8]3 years ago

7 0

Answer:

The process of selection conducted under human direction.

Explanation:

For example, by allowing only like individuals to breed, breeders have created the great variety of dog breeds and crop plants

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Multiple Questions, Brainliest and 98 points to whoever answers all questions correctly

otez555 [7]

Question 1

The average atomic mass of element is 84.66

calculation

Average atomic mass is of an element is the sum of masses of its isotope each multiplied by its natural abundance.

that is.

[(50.50 x 83.75) /100] + [( 30.25 x 84.45)/100] + [(,9.25 x 87.40)/100]

= 42.29 +25.55 +16.82= 84.66

Question 2

fill the table

symbol element protons neutrons Electrons mass No Atomic No

Cs-133 cesium 55 78 55 133 55

Na-23 sodium 11 12 11 23 11

Ne 22 Neon 10 12 1 0 22 10

Au -197 Gold 79 118 79 197 79

Question 3

The moles of tungsten that are in 93.50 grams are 0.509 moles

moles= mass/molar mass

molar mass of tungsten = 183.84 g/mol

moles is therefore= 93.50 g/ 183.84 g/mol= 0.509 moles

question 4

CO2 molecules at STP are 1.547 x10^23 molecules

Step 1: find the moles of CO2

At STP 1 mole of a gas= 22.4 l

? =5.75 L

by cross multiplication

= (5.75 L x 1 mole)/ 22.4 L= 0.257 moles

Step 2: use the Avogadro's constant to calculate the number of molecule

that is 1 moles = 6.02 x10^23 molecules

0.257 moles= ? molecules

by cross multiplication

=(0.257 moles x 6.02 x 10^23) / 1 mole = 1.547 x10^23 molecules

question 5

The number of calcium atoms is 3.82 x10^24 atoms

Step 1: find the moles of calcium

= 253.50 g /40 g/mol= 6.34 moles

Step 2: use the Avogadro's law to calculate the number of atoms.

that is 1 mole= 6.02 x 10^23 atoms

6.34 moles= ? atoms

=6.34 x 6.02 x10^23 = 3.82 x10^24 atoms

Question 6

mass in grams of NiBr2 is 126.97 grams

Step 1: by use of Avogadro's law constant calculate the number of moles

that is 1 mole = 6.02 x 10^23

? = 3.50 x 10^23

by cross multiplication

= (1 mole x 3.50 x10^23) / 6.02 x10^23 =0.581 moles

step 2: calculate the mass

mass =moles x molar mass

= 0.581 moles x218.53 g/mol = 126.97 grams

Bonus question

The molecules of water= 1.00 x10^26 molecules

calculation

convert liters into ml

= 3 x 1000 = 3000 ml

find the mass of water

= density x volume

=3000 x0.998 2994 grams

find the moles of water=mass/molar mass

= 2994 g/ 18 g/mol= 166.33 moles

Use Avogadro's constant to calculate the molecules of water

that is 1 mole= 6.02 x10^23 molecules

166.33 moles= ? molecules

= (166.33 moles x6.02 x10^23 molecules) / 1 mole = 1.00 x10^26 molecules

3 0

3 years ago

Read 2 more answers

1.I make my cup of coffee in the morning by pouring boiling water over ground-up coffee beans held in a special piece of paper a

777dan777 [17]

Answer:

Filtration

Explanation:

Filtration is a physical separation technique that is used to separate solids from liquids or gases. The process involves the use of a filter which allows just the liquid to pass through.

In this case, the coffee beans is the solid and the boiling water is the liquid. The special piece of paper is the medium (filter) through which the coffee is collected.

The coffee coming through the special piece of paper (filter) is called a filtrate.

Filtration is used in the preparation of the cup of coffee.

5 0

3 years ago

Calculate the volume of 2.0116 x 10^23 molecules of nh3 gas trapped in a container at a pressure of 2280.0 mmhg and a temperatur

OLEGan [10]

The problem in this question can be solved using the ideal gas formula. Ideal gas formula show interaction between the pressure, volume, temperature and the number of molecules.

n= number of molecule/ avogadro number
n= (2.0116 x 10^23 / 6.02*10^23)= 1/3 mole

T= celcius + 273.15
T= (41+273.15) K=314.15

P=2280 mmHg / (760mmHg/atm)= 3 atm

PV=nRT
V= nrT/ P
V= 1/3 moles * (0.08205 L atm / mol·K) * 314.15 K / 3 atm
V= 2.864 L

5 0

3 years ago

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

What do tissues combine to form?

elena55 [62]

Answer is D organs because cell forms tissues, tissues form organs and organs forms the organ system

4 0

3 years ago

Read 2 more answers