What was the process that Marie curie used to turn 8 tons of rubble into 1/5 of a teaspoon of radium?

Which source should be avoided when conducting scientific research? encyclopedias

WINSTONCH [101]

Wikipedia
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3 0

3 years ago

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Choose the atom with:

nata0808 [166]

Answer:

a )Li

b)O

c)F

Explanation:

a) Li-1s^2 2s^1

F-1s^2 2s^2 2p^5

it is easy to pull out e- from 2p orbit than 2s because 2s orbit is close to nucleus.Therefore Li have high ionisation enthalpy

b)oxygen ion is larger than Na because o have fewer proton

c)F because it requires only 1e to achieve stable noble gas configuration.Therefore to achieve stable nobke gas electonic configuration it accept 1e.

6 0

3 years ago

A helium-filled balloon at 310.0 K and 1 atm, contains 0.05 g He, and has a volume of 1.21 L. It is placed in a freezer (T = 235

trapecia [35]

Answer : The value of $\Delta E$ of the gas is 2.79 Joules.

Explanation :

First we have to calculate the moles of helium.

$\text{Moles of helium}=\frac{\text{Mass of helium}}{\text{Molar mass of helium}}$

Molar mass of helium = 4 g/mole

$\text{Moles of helium}=\frac{0.05g}{4g/mole}=0.0125mole$

Now we have to calculate the heat.

Formula used :

$q=nc_p\Delta T\\\\q=nc_p(T_2-T_1)$

where,

q = heat

n = number of moles of helium gas = 0.0125 mole

$c_p$ = specific heat of helium = 20.8 J/mol.K

$T_1$ = initial temperature = 310.0 K

$T_2$ = final temperature = 235.0 K

Now put all the given values in the above formula, we get:

$q=nc_p(T_2-T_1)$

$q=(0.0125mole)\times (20.8J/mol.K)\times (235.0-310.0)K$

$q=-19.5J$

Now we have top calculate the work done.

Formula used :

$w=-p\Delta V\\\\w=-p(V_2-V_1)$

where,

w = work done

p = pressure of the gas = 1 atm

$V_1$ = initial volume = 1.21 L

$V_2$ = final volume = 0.99 L

Now put all the given values in the above formula, we get:

$w=-p(V_2-V_1)$

$w=-(1atm)\times (0.99-1.21)L$

$w=0.22L.artm=0.22\times 101.3J=22.29J$

conversion used : (1 L.atm = 101.3 J)

Now we have to calculate the value of $\Delta E$ of the gas.

$\Delta E=q+w$

$\Delta E=(-19.5J)+22.29J$

$\Delta E=2.79J$

Therefore, the value of $\Delta E$ of the gas is 2.79 Joules.

3 0

3 years ago

(8x-1) (3x + 4) (3x + 9)

Mnenie [13.5K]

Answer: -9x^2 -31x -36 I hope this helped! ~GalaxyGamingKitty Can I have Brainliest if it is right?

3 0

3 years ago

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Problem: Convert 30 cm to mm. Need full process pls help

marta [7]

Answer: 300mm

Explanation:

30cm x (10mm/1cm) x (1mm/1mm) = 300mm

Btw, I'm not sure about the (1mm/1mm).

3 0

3 years ago