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3 years ago

Which structure of the respiratory system connects the pharynx to the trachea?

Chemistry

2 answers:

Citrus2011 [14]3 years ago

8 0

Answer:

Larynx

Explanation:

It is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs.

muminat3 years ago

6 0

Larynx connects the pharynx to the trachea and is also part of the respiratory system

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6 At STP, which element is a good conductor of electricity?(1) chlorine (3) silver

alexgriva [62]

For an object to conduct electricity it should have free or delocalised electrons that are free to pass the charge and hence take part in conducting electricity.
From the given choices
Chlorine is a halogen existing as a diatomic gas. Iodine too is a halogen and 2 Iodine atoms held together by covalent bond. Cl - Cl bonds and I-I bonds are covalent bonds. the outer electrons of Cl and I take part in covalent bonds therefore they are fixed and not free to move about. therefore no free electrons to conduct electricity.
Sulfur is a solid that too is held together by covalent bonds so it does not have free electrons to conduct electricity.

Silver is a metal and a general property of metals are their ability to conduct electricity.
metal structure are metal ions tightly packed together. when the metal atoms are tightly packed their valence electrons are removed and delocalised. Positively charged metal ions are embedded in a sea of delocalised electrons.
therefore there are delocalised electrons that can conduct electricity

answer is 3) silver

3 0

2 years ago

Read 2 more answers

Uranium-238 decays to lead-206 with a half-life of 4.5 x 109 yr. Determine how much uranium-238 decays in milligrams (to three s

Mamont248 [21]

Answer:

2.15 mg of uranium-238 decays

Explanation:

For decay of radioactive nuclide-

$N=N_{0}.(\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}$

where N is amount of radioactive nuclide after t time, $N_{0}$ is initial amount of radioactive nuclide and $t_{\frac{1}{2}}$ is half life of radioactive nuclide

Here $N_{0}=4.60 mg$ , $t=4.1\times 10^{9}yr$ and $t_{\frac{1}{2}}=4.5\times 10^{9}yr$

So, $N=(4.60mg)\times (\frac{1}{2})^{\frac{4.1\times 10^{9}}{4.5\times 10^{9}}}$

so, N = 2.446 mg

mass of uranium-238 decays = (4.60-2.446) mg = 2.15 mg

3 0

3 years ago

Calculate the osmotic pressure of 20 m solution of LiCl at 25C

Soloha48 [4]

Answer:

979 atm

Explanation:

To calculate the osmotic pressure, you need to use the following equation:

π = i MRT

In this equation,

-----> π = osmotic pressure (atm)

-----> i = van't Hoff's factor (number of dissolved ions)

-----> M = Molarity (M)

-----> R = Ideal Gas constant (0.08206 L*atm/mol*K)

-----> T = temperature (K)

When LiCl dissolves, it dissociates into two ions (Li⁺ and Cl⁻). Therefore, van't Hoff's factor is 2. Before plugging the given values into the equation, you need to convert Celsius to Kelvin.

i = 2 R = 0.08206 L*atm/mol*K

M = 20 M T = 25°C + 273.15 = 298.15 K

π = i MRT

π = (2)(20 M)(0.08206 L*atm/mol*K)(298.15 K)

π = 979 atm

5 0

2 years ago

What mass of chromium would be produced from the reaction of 57.0 g of potassium with 199 g of chromium(II) bromide according to

fredd [130]

Answer:

Mass of Chromium produced = 37.91 grams

Explanation:

2K + CrBr₂ → 2KBr + Cr

2mole 1 mole 1 mole

mass of Potassium = 57.0 grams

molar mass of Potassium = 39.1 g/mol

no of moles of Potassium = 57.0 / 39.1 = 1.458 moles

mass of CrBr₂= 199 grams

molar mass of CrBr₂ = 211.8 gram/mole

no of moles of CrBr₂ = 199 / 211.8 = 0.939 mole

From chemical equation

1 mole of CrBr₂ = 2 moles of K

∴ 0.939 moles of CrBr₂ = ?

⇒ 0.939 x 2/1 = 1.878 moles of K

1.878 moles of K is needed, but there is 1.458 moles of K. So, Potassium is completed first during the reaction . Hence, Potassium is limiting reagent. and CrBr₂ is excess reagent .

From chemical equation

2 moles of K = 1 mole of Cr

∴ 1.458 moles of K = ?

⇒ 1.458 x 1/ 2 = 0.729 moles of Cr

no of moles of Cr formed = 0.729 moles

molar mass of Cr = 52.0 g/mol

mass of one mole of Cr = 52.0 grams

mass of 0.729 moles of Cr = 52.0 x 0.729 = 37.908 grams

mass of Chromium produced = 37.91 grams

6 0

3 years ago

Which indicator would show a pH change from 6 to 7?

tatyana61 [14]

Answer:

Explanation:

1. litmus paper is used when showing a change between a greater range in ph levels - so A and D are automatically a no.

2. methyl red is used to show a range in ph levels between 4.8-6

3. Option C is the only one left so im going to assume its C because its definitely not A, B, or D

7 0

2 years ago