Magnesium oxide is an ionic compound that can be used as a building material. MO2 is actually a raw material that used in producing cement for building houses, buildings, and other constructions.
Many old structures were made of limestones. Limestone is from Calcium Carbonate (CaCO3) which is an ionic compound and can be used as a building material too.
V = [4/3]π r^3 => [dV / dr ] = 4π r^2
[dV/dt] = [dV/dr] * [dr/dt]
[dV/dt] = [4π r^2] * [ dr/ dt]
r = 60 mm, [dr / dt] = 4 mm/s
[dV / dt ] = [4π(60mm)^2] * 4mm/s = 180,955.7 mm/s
If it is a true or false question then it is true
