2000 BC and was found in tubes in Egyptian tombs dated from 1500BC
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Answer:
3.01×10²³ atoms of calcium
Explanation:
number of moles = number of atoms/Avogadro's constant
n = N/NA
N = n×NA = 0.500 mol×6.02×10²³ mol^-1
N = 3.01×10²³ atoms of calcium
Answer:
The standard change in free energy for the reaction = - 437.5 kj/mole
Explanation:
The standard change in free energy for the reaction:
4 KClO₃ (s) → 3 KClO₄(s) + KCl(s)
Given that ΔGf(KClO3(s)) = -290.9 kJ/mol;
ΔGf(KClO4(s)) = -300.4 kJ/mol;
ΔGf(KCl(s)) = -409 kJ/mol
According to Hess's law
ΔGr (Free energy change of reaction)= ∑(Product free energy - reactant free energy)
⇒ ΔGr⁰ = {3 x (-300.4) + (-409)} - {3 x (- 290.9)}
= - 901.2 - 409 + 872.7
= - 437.5 kj/mole
Answer:
9g
Explanation:
Since..., Density = mass/volume
;Firstly calculate the volume change of the water when the metal is placed in,
;Volume = 26.47 - 21.25
;Volume = 5.22 mL
Hence the mass of the ore;
; Making mass the subject of formula in the above equation,
Mass = Density × Volume
; Mass = 1.72 × 5.22
; Hence the mass = 8.9784
= 9g
Answer:
Volcanologists use many different kinds of tools including instruments that detect and record earthquakes (seismometers and seimographs), instruments that measure ground deformation (EDM, Leveling, GPS, tilt), instruments that detect and measure volcanic gases (COSPEC), instruments that determine how much lava is moving underground (VLF, EM-31), video and still cameras, infrared cameras, satellite imagers, webcams, etc!
Explanation:
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