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3 years ago

On average, how many hours of sleep do teenagers need each night? 7 hours 7.5 hours 8 hours 8.5 hours

Chemistry

2 answers:

Marrrta [24]3 years ago

5 0

Answer:

8 to 8.5 since that is the recommended and people usualy sleep more than that

Vera_Pavlovna [14]3 years ago

3 0

Answer:

7.5

Explanation:

i listened to the other dude and got it wrong but it showed this answer to be correct

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How many grams of na3po4 will be needed to produce 650. mL of a solution that has a concentration of na+ ions of 1.40 M

SashulF [63]

Answer:

I think its 1.40M Na^+ we convert to Na3PO4 which means we need 1.40M x (1 mole Na3PO4/3 mol Na^+) = 1.40 x 1/3 = 0.467 M Na3PO4.

Explanation:

7 0

4 years ago

Part 1: A cylinder containing 20.0 L of compressed nitrogen is connected to an empty (evacuated) vessel with an unknown volume.

baherus [9]

Answer:

The volume of the vessel is 250 L

Partial pressure of hydrogen = 189 torr

Explanation:

Using Boyle's law

${P_1}\times {V_1}={P_2}\times {V_2}$

Given ,

V₁ = 20.0 L

V₂ = ?

P₁ = 25 atm

P₂ = 2 atm

Using above equation as:

${P_1}\times {V_1}={P_2}\times {V_2}$

${25}\times {20.0}={2}\times {V_2}$

${V_2}=\frac {{25}\times {20.0}}{2}\ L$

${V_2}=250\ L$

<u>The volume of the vessel is 250 L.</u>

According to Dalton's law of partial pressure:-

$P_{H_2}=Mole\ fraction\times Total\ Pressure$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ H_2=\frac {n_{H_2}}{n_{H_2}+n_{He}}$

Also,

Mole fraction of H₂ = 1 - Mole fraction of He = 1 - 0.75 = 0.25

So,

Total pressure = 756 torr

Thus,

$P_{H_2}=0.25\times 756\ torr$

<u>Partial pressure of hydrogen = 189 torr.</u>

7 0

3 years ago

can you guys please help me answer this, I have an assignment and I have to submit it in 5 minutes, please help

Alborosie

Answer:

Explanation:

kinetic energy can be calculated using the formula

=1/2*mass*velocity or speed ^2

7 0

3 years ago

How can we reduce our carbon footprint

asambeis [7]

Answer:

reduce using fossil fuels

Explanation:

fossil fuels are increasing our carbon footprint and so are green house gasses but we can't have too little greenhouse gasses or too much greenhouse gasses

4 0

3 years ago

How can valid conclusions from the growth rate calculations be applied in a biotechnological or biomedical context ?

Igoryamba

Growth rate calculations and their conclusions can be used in biomedical contexts when organisms are being grown for the synthesis of compounds or other purposes.

7 0

3 years ago