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AnnyKZ [126]
3 years ago
5

Fill in the blank. A ___ is a substance that cannot be separated into simpler substances by physical or mechanical methods such

as filtering, boiling, or sifting
Chemistry
2 answers:
Ganezh [65]3 years ago
8 0
An element cannot be broken down any further. Elements can be found on the periodic table

PolarNik [594]3 years ago
8 0
I think it's a pure substance 
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Consider the reaction between acetylene, c2h2, and oxygen in a welding torch: 2c2h2(g) + 5o2(g) → 4co2(g) + 2h2o(g) if 5.4 moles
fredd [130]
<span>                                      2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
   from the reaction     2 mol                              4 mol
from the problem      5.4 mol                         10.8 mol

M(CO2) = 12.0 +2*16.0 = 44.0 g/mol
10.8 mol CO2 * 44.0 g CO2/1 mol CO2 = 475.2 g CO2 </span>≈480 = 4.8 * 10² g
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4 0
3 years ago
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Carbon-14 has a half-life of 5720 years and this is a fast-order reaction. If a piece of wood has converted 75 % of the carbon-1
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11445.8years

Explanation:

Half-life of carbon-14 = 5720 years

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3 years ago
It takes 281.7 kJ of energy to remove 1 mole of electrons from the atoms on the surface of lithium metal. If lithium metal is ir
Alex17521 [72]

Answer:

The maximum kinetic energy of electron is = 2.93 × 10^{-19} Joule

Explanation:

We know that total energy

E = \frac{hc}{\lambda}  ------------ (1)

Here h = plank's constant = 6.62 × 10^{-34} J s

c = speed of light = 3 × 10^{8} \frac{m}{s}

\lambda = 261 nm = 261  × 10^{-9} m

Put all these values in equation (1) we get

E = 7.6   × 10^{-19} J

We know that

Total energy = Energy to remove an electron + K.E of electron

Energy to remove an electron = \frac{281.7 (1000)}{(6.023)10^{23} }

Energy to remove an electron = 4.67  × 10^{-19} J

K.E of electron = Total energy - Energy to remove an electron

K.E of electron = 7.6   × 10^{-19} -  4.67  × 10^{-19}

K.E of electron = 2.93 × 10^{-19} Joule

Therefore the maximum kinetic energy of electron is = 2.93 × 10^{-19} Joule

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D. Volcanoes formed most of them through eruption.
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