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3 years ago

12

Which structure of the cell controls what goes in and comes out of the cell? cell _________ Which structure is a strong layer ar

ound plant cells? cell ________

2 answers:

Dmitrij [34]3 years ago

8 1

Answer:

cell membrane

Explanation:

3 years ago

Your wrong I did it and its not right

masya89 [10]3 years ago

6 1

First one is cell Membrane and the second one is cell Wall

3 years ago

Your wrong I did it and its not right

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How many joules of heat must be absorbed by 500g h2O @ 50CELCIUS to convert to steam @ 120 celcius?

nadya68 [22]

Answer:

Q = 1267720 J

Explanation:

Qt = QH2O + ΔHv

∴ QH2O = mCpΔT

∴ m H2O = 500 g

∴ Cp H2O = 4.186 J/g°C = 4.183 E-3 KJ/g°C

∴ ΔT = 120 - 50 = 70°C

⇒ QH2O = (500 g)(4.183 E-3 KJ/g°C)(70°C) = 146.51 KJ

∴ ΔHv H2O = 40.7 KJ/mol

moles H2O:

∴ mm H2O = 18.015 g/mol

⇒ moles H2O = (500 g)(mol/18.015 g) = 27.548 mol H2O

⇒ ΔHv H2O = (40.7 KJ/mol)(27.548 mol) = 1121.21 KJ

⇒ Qt = 146.51 KJ + 1121.21 KJ = 1267.72 KJ = 1267720 J

5 0

3 years ago

To calculate the percentage of people who have a particular allele population studies are conducted to collect data.true or fals

kondaur [170]

I think is is going to be truth because

6 0

3 years ago

Which type of reaction?

polet [3.4K]

condensation polymerization, since a byproduct of the reaction is a single molecule of water (hence condensation of water)

addition polymerization is if you add the two polymers together like blocks and should have no byproducts

esterification is when you combine an organic acid with an alcohol. Since neither of the two polymers look like acids, you can rule this out.

never heard of saponification, Im an mechanical engineer not an organic chemist

3 0

3 years ago

Which of the following do you pracrice at home

S_A_V [24]

You didn’t post the photo or full question

8 0

3 years ago

The half-life of a positron is very short. It reacts with an electron, and the masses of both are converted to two gamma-ray pho

sp2606 [1]

Explanation:

(a) It is known that relation between energy and mass is as follows.

$E = 2 \times mc^{2}$

where, E = energy

m = mass

c = speed of light = $3 \times 10^{8}$ m/s

As it is given that mass is $9.109 \times 10^{-31}$ kg. So, putting the given values into the above formula as follows.

$E = 2 \times mc^{2}$

= $2 \times 9.109 \times 10^{-31} kg \times 3 \times 10^{8}m/s$

= $1.638 \times 10^{-13} J$

Therefore, we can conclude that the energy produced by the reaction between one electron and one positron is $1.638 \times 10^{-13} J$ .

(b) When gamma ray photons are produced then they will have the same frequency. Relation between energy and frequency is as follows.

E = $h \times \nu$ ..... (1)

where, h = plank's constant = $6.626 \times 10^{-34} J.s$

$\nu$ = frequency

Also, $E = 2 \times mc^{2}$ ........ (2)

Hence, equating equations (1) and (2) as follows.

$h \times \nu$ = $2 \times mc^{2}$

So,

$6.626 \times 10^{-34} Js \times \nu$ = $1.638 \times 10^{-13} J$

$\nu$ = $1.236 \times 10^{20} Hz$

Thus, we can conclude that the frequency is $1.236 \times 10^{20} Hz$ .

5 0

3 years ago