Acarbon atom has how many valence electrons?

How much heat is required to convert 0.3 kg of ice at 0°c to water at the same temperature

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.