Answer:
Formation. When the solar system settled into its current layout about 4.5 billion years ago, Earth formed when gravity pulled swirling gas and dust in to become the third planet from the Sun. Like its fellow terrestrial planets, Earth has a central core, a rocky mantle and a solid crust.
In an acid-base titration, the neutralization reaction between the acid and base can be measured with either a color indicator or a pH meter. In this experiment, aphenolphthalein<span> color indicator will be </span>used<span>.
</span>Phenolphthalein<span> is colorless in acidic solutions and pink in basic solutions.
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Answer:

Explanation:
¡Hola!
En este caso, dado que estamos tratando con problem sobre porcentaje peso/peso de hierro, arena, cobre y aluminio, primero debemos calcular la masa inicial de estos dos primeros en la mezcla original de acuerdo con:

Ahora si podemos calcular la masa de la mezcla final como la suma de las masas de todos los constituyentes de la mezcla:

Finalmente, podemos calcular los porcentajes P/P como se muestra a continuación:

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Answer : Option A)
45.5%
Explanation : We use the formula of calculating energy efficiency which is as,
η (in %)= [

] X 100
where η is energy efficiency,
and P values are for energy out and in.
So plugging the given values, we get,
η (in %) = (11825.5 / 25978.8) X 100 =
45.5 %
Just reorder the equation
Density= mass/volume