We know that the equation for density is:

where D is the density, m is the mass in grams, and V is the volume.
Given two of the variables, we can then solve for density:

So therefore, we now know that the density of carbon dioxide gas is 0.00196g/mL.
Answer:
Mg
Explanation:
Magnesium has a valency of +2
Answer: 1 molar NaOH contains 40 grams of NaOH per every liter of water
Explanation:
so 2 M NaOH contains twice that amount, ie. 80 grams per liter. Then, ine 250 ml of weater, there should be 80/4 = 20 grams of solid NaOH dissolved.