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3 years ago

Please helpppppppppp

Chemistry

2 answers:

IgorC [24]3 years ago

4 0

Answer:

Plants take carbon dioxide from the air and use it to make food.

Explanation:

kipiarov [429]3 years ago

4 0

the carbon cycle is the process in which carbon travels from the atmosphere into organisms and the earth and then back into the atmosphere

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Uranium and radium are found in many rocky soils throughout the world. Both undergo radioactive decay, and one of the products i

Inessa05 [86]

(a) 0.15 Bq/L is the safe level of radon in Bq/L of air/

<h3>Radionuclides: Uranium and Radium</h3>

So you've just had your water tested and the lab results are telling you that you've got radionuclides.

Radionuclides are radioactive isotopes or unstable forms of elements. Radioactivity is the release of energy, radiation, that occurs when these unstable elements decay or breakdown into more stable elements. This process is known as radioactive decay and is measured by the half-life of the element. The half-life is the time required for half of the original element to decay. The half-life for radionuclides can range from a few thousands of a second to a few billion years.

The two most common radionuclides found in groundwater supplies are Uranium and Radium. Uranium and Radium are naturally occurring elements that are found throughout the Mid-Atlantic and Northeastern United States in bedrock deposits like shale or granite deep below the surface. Rather than the glowing green rocks often portrayed in cinema or television, uranium and radium are found in ores mixed with other minerals and metals.

Uranium is the largest naturally occurring element on earth, nearly 70% denser than lead, and exists naturally as three different isotopes: U-234, U-235, and U-238, with U-238 and U-235 being the most common. U-235 is the preferred isotope for nuclear power generation. All three forms of uranium have the same chemical and physical properties, but have different radioactive properties.

In very low pH conditions, uranium exists in a cation oxidized form UO2, but it is most commonly present as anionic compounds UO2(CO3)2 and UO2(CO3)3. As uranium decays naturally over time, it releases radiation and forms new elements like radium, lead, and radon gas.

Learn more about radon

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5 0

1 year ago

I need help. ASAP! Look at the picture below. (2)

ozzi

C. MgCl2

This structure forms a ionic bond, which are generally stronger than covalent bonds. All of the other choices are covalent.

5 0

4 years ago

Calcium has a cubic closest packed structure as a solid. Assuming that calcium has an atomic radius of 197 pm, calculate the den

NISA [10]

Answer:

$\rho=1.54\ g/cm^3$

Explanation:

The expression for density is:

$\rho=\frac {Z\times M}{N_a\times {{(Edge\ length)}^3}}$

$N_a=6.023\times 10^{23}\ {mol}^{-1}$

M is molar mass of Calcium = 40.078 g/mol

For cubic closest packed structure , Z= 4

$\rho$ is the density

Radius = 197 pm = $1.97\times 10^{-8}\ cm$

Also, for fcc, $Edge\ length=2\sqrt{2}\times radius=2\sqrt{2}\times 1.97\times 10^{-8}\ cm=5.572\times 10^{-8}\ cm$

Thus,

$\rho=\frac{4\times \:40.078}{6.023\times \:10^{23}\times \left(5.572\times 10^{-8}\right)^3}\ g/cm^3$

$\rho=\frac{160.312}{10^{23}\times \:6.023\left(10^{-8}\times \:5.572\right)^3}\ g/cm^3$

$\rho=\frac{160.312}{10^{23}\times \:1.04195E-21}\ g/cm^3$

$\rho=\frac{160.312}{104.19483}\ g/cm^3$

$\rho=1.54\ g/cm^3$

7 0

3 years ago

QUESTION 3 Consider a solution containing 0.80 M NaF and 0.80 M HF. Calculate the moles of HF and the concentration of HF after

Lisa [10]

Answer:

0.056moles HF and 0.70M

Explanation:

When a strong acid is added to a buffer, the acid reacts with the conjugate base.

In the system, NaF and HF, weak acid is HF and conjugate base is NaF. The reaction of NaF with HCl (Strong acid) is:

NaF + HCl → HF + NaCl

Initial moles of NaF and HF in 60.0mL of solution are:

NaF:

0.0600L × (0.80mol / L)= 0.048 moles NaF

HF:

0.0600L × (0.80mol / L)= 0.048 moles HF

Then, the added moles of HCl are:

0.0200L × (0.40mol / L) = 0.008 moles HCl.

Thus, after the reaction, moles of HF produced are 0.008 moles + the initial 0.048moles of HF, moles of HF are:

0.056moles HF

In 20.0mL + 60.0mL = 80.0mL = 0.0800L, molarity of HF is:

0.056mol HF / 0.0800L = 0.70M

6 0

3 years ago

1. What role does energy play in sound?

Lilit [14]

Answer:

1. Sound is a energy (mechanical)produced by vibrating objects and sound energy is movement of energy through particles.

2.Space occupied by the substance

3.Propagation of Sound Wave and particles of the medium

4.High-Frequency(Ultrasonic wave)

Explanation:

1.Sound is the form of energy which causes sensation of hearing to our ear.It is produce by vibrating objects. When the objects vibrate(to and fro motion) ,they pushes the particles of medium creating the region of high density called compression .When the particles moves backward ,they creates a region of low density called Rarefaction.This pattern repeats indefinitely.

2.Volume is the quantity of three dimensional space occupied by substances like solid,liquid and gases. The SI unit of volume is

$m^{3}$

In metric system unit of volume is liter

3. Longitudinal Waves: Waves in which displacement of the medium particles are parallel(in the same direction) to the propagation of wave.

Sound wave is longitudinal wave.Hence its particles moves in the same direction as the wave (energy)travel.

4.Frequency: The number of times sound wave passes a given point in one second.Its SI unit is Hertz(Hz).

Frequency of vibration decides the Pitch of the sound waves producing them.

A sound wave of High Pitch means it is oscillating rapidly(at high speed).These are also called Ultrasonic waves. These have frequency more than 20000 Hz. Human being can't hear ultrasonic waves.

7 0

3 years ago