El universo ha existido siempre aproximadamente tal y como hoy lo conocemos. Es homogéneo e isotropa es decir, a gran escala tiene la misma aparienda, independientemente del punto desde donde se observe. El sol
solo es una de las centenares de miles de estrellas que forman nuestra calcio, la Vallcten. Y esta, a su ve
solo es una galaxia tipica entre centerares de miles de galaxias distribuidas por el Universo. No existe un centro
sino una extensión infinita de galanias

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2