An isotope of mercury has 80 protons and 120 neutrons. what is the mass number of this isotope.

Agas mixture with a total pressure of 745 mmhg contains each of the following gases at the indicated partial pressures: co2, 245 mmhg ; ar, 119 mmhg ; and o2, 163 mmhg . the mixture also contains helium gas. part a what is the partial pressure of the helium gas? phe p h e = nothing mmhg request answer part b what mass of helium gas is present in a 10.2-l sample of this mixture at 283 k ? m m = nothing g request answer

Supongamos que estás estudiando dos estrellas. ambas estrellas tienen la misma magnitud aparente, pero la estrella a tiene una magnitud absoluta mayor que la estrella b. ¿que puedes decir acerca de la distancia a la tierra de estas dos estrellas?

During trial 2, what allowed you to determine that aluminum was the limiting reactant? check all that apply. all of the copper dissolved. all of the aluminum dissolved. the solution turned clear. the number of grams of copper(ii) chloride used in the reaction was greater than the number of grams of aluminum. the molar ratio of copper(ii) chloride to aluminum was greater than 3: 2, the equation’s molar ratio.