Magnesium carbonate decomposes on heating to form magnesium oxide and carbon dioxide as shown. MgCO3 -> MgO + CO2

How much magnesium carbonate is needed to make 10.0g of magnesium oxide?

A. 3.5g
B. 10.5g
C. 21.0g
D. 6.5g

please answer, I have a test right now​

Asample of air with a volume of 2.20m3 at a pressure of 105 kpa and a temperature of 30c is cooled to 10c and the pressure is reduced to 75.0 kpa. what is the new volume? 6.9 1.34 2.56 43.0 2.88

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

What is the molarity of the solution produced when 145 g of nacl is dissolved in sufficient water to prepare 2.75 l of solution?