What volume (measured at stp) will 3.75 grams of helium gas occupy?

Find the mass, in grams, of 5.00*10^23 molecules of f2

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?

Maya wrote if you step to describe how carbon circulates between the atmosphere and living organisms