La velocidad de la luz en el vacío es de 2.998 x10 a la 8 m/s. Expresar en km/h

1.079x10⁹ km/h

Explanation:

Primero convertimos 2.998 x 10⁸ m/s a km/s, teniendo en cuenta que 1 kilometro son 1000 metros:

2.998x10⁸ m/s * = 2.998x10⁵ km/s

Finalmente convertimos 2.998x10⁵ km/s a km/h, teniendo en cuenta que hay 60 segundos en un minuto y hay 60 minutos en una hora.

2.998x10⁵ km/s * = 1.079x10⁹ km/h

The effect of an insoluble impurity, such as sand, on the observed melting point of a compound would be none. It will not depress or elevate the melting point of the compound. Instead, it would affect the reading if you are trying to determine the melting point of the compound. This is because you might be missing  the actual melting point of the compound since you will be waiting for the whole sample to liquify. You would not be able to determine exactly that temperature because of the insoluble impurity would have a different melting point than that of the compound.